A standardised diagnostic approach to pituitary neuroendocrine tumours (PitNETs): a European Pituitary Pathology Group (EPPG) proposal

Histopathology of growth hormone-secreting pituitary tumors: State of the art and new perspectives

Somatotroph (GH) adenomas/PitNETs typically arise from adenohypophysis and are biochemically active, leading to acromegaly and gigantism. More rarely, they present with ectopic origin and do not present overt biochemical or clinical features (silent variants). Histopathological examination should consider the clinical and radiological background, and include multiple steps assessing tumor morphology, pituitary transcription factors (PTFs), hormone secretion, proliferation markers, granulation, and somatostatin receptors (STRs), aimed at depicting as better as possible tumor origin (in case of non-functioning and/or metastatic tumor), and clinical behavior, including response to treatment. GH-secreting tumors are part of the Pit-1 family tumors and can secrete GH only (pure somatotrophs) or co-secrete prolactin (mixed tumors; in this case, various histological subtypes have been identified). Each subtype presents unique radiological, biochemical, and clinical characteristic. Therefore, the integration of biochemical, clinical, radiological, and histopathological elements is fundamental for proper diagnosis and management of pituitary adenomas/PitNETs, to be performed in referral Centers. In more recent times, the importance of genetic and epigenetic evaluation in the characterization of pituitary tumors (i.e., early identification of aggressive variants) has been outlined by some large studies, with the intention of improving targeted treatments.

Consensus guideline for the diagnosis and management of pituitary adenomas in childhood and adolescence: Part 1, general recommendations

Tumours of the anterior part of the pituitary gland represent just 1% of all childhood (aged <15 years) intracranial neoplasms, yet they can confer high morbidity and little evidence and guidance is in place for their management. Between 2014 and 2022, a multidisciplinary expert group systematically developed the first comprehensive clinical practice consensus guideline for children and young people under the age 19 years (hereafter referred to as CYP) presenting with a suspected pituitary adenoma to inform specialist care and improve health outcomes. Through robust literature searches and a Delphi consensus exercise with an international Delphi consensus panel of experts, the available scientific evidence and expert opinions were consolidated into 74 recommendations. Part 1 of this consensus guideline includes 17 pragmatic management recommendations related to clinical care, neuroimaging, visual assessment, histopathology, genetics, pituitary surgery and radiotherapy. While in many aspects the care for CYP is similar to that of adults, key differences exist, particularly in aetiology and presentation. CYP with suspected pituitary adenomas require careful clinical examination, appropriate hormonal work-up, dedicated pituitary imaging and visual assessment. Consideration should be given to the potential for syndromic disease and genetic assessment. Multidisciplinary discussion at both the local and national levels can be key for management. Surgery should be performed in specialist centres. The collection of outcome data on novel modalities of medical treatment, surgical intervention and radiotherapy is essential for optimal future treatment.

Primary Cilia as a Tumor Marker in Pituitary Neuroendocrine Tumors

Pituitary neuroendocrine tumors (PitNETs) account for approximately 15% of all intracranial neoplasms. Although they usually appear to be benign, some tumors display worse behavior, displaying rapid growth, invasion, refractoriness to treatment, and recurrence. Increasing evidence supports the role of primary cilia (PC) in regulating cancer development. Here, we showed that PC are significantly increased in PitNETs and are associated with increased tumor invasion and recurrence. Serial electron micrographs of PITNETs demonstrated different ciliation phenotypes (dot-like versus normal-like cilia) that represented PC at different stages of ciliogenesis. Molecular findings demonstrated that 123 ciliary-associated genes (eg, doublecortin domain containing protein 2, Sintaxin-3, and centriolar coiled-coil protein 110) were dysregulated in PitNETs, representing the upregulation of markers at different stages of intracellular ciliogenesis. Our results demonstrate, for the first time, that ciliogenesis is increased in PitNETs, suggesting that this process might be used as a potential target for therapy in the future.

The Multibiomarker Acro-TIME Score Predicts fg-SRLs Response: Preliminary Results of a Retrospective Acromegaly Cohort

CONTEXT

The prompt control of acromegaly is a primary treatment aim for reducing related disease morbidity and mortality. First-generation somatostatin receptor ligands (fg-SRLs) are the cornerstone of medical therapies. A non-negligible number of patients do not respond to this treatment. Several predictors of fg-SRL response were identified, but a comprehensive prognostic model is lacking.

OBJECTIVE

We aimed to design a prognostic model based on clinical and biochemical parameters, and pathological features, including data on immune tumor microenvironment.

METHODS

A retrospective, monocenter, cohort study was performed on 67 medically naïve patients with acromegaly. Fifteen clinical, pathological, and radiological features were collected and analyzed as independent risk factors of fg-SRLs response, using univariable and multivariable logistic regression analyses. A stepwise selection method was applied to identify the final regression model. A nomogram was then obtained.

RESULTS

Thirty-seven patients were fg-SRLs responders. An increased risk to poor response to fg-SRLs were observed in somatotropinomas with absent/cytoplasmatic SSTR2 expression (OR 5.493 95% CI 1.19-25.16, P = .028), with low CD68+/CD8+ ratio (OR 1.162, 95% CI 1.01-1.33, P = .032). Radical surgical resection was associated with a low risk of poor fg-SRLs response (OR 0.106, 95% CI 0.025-0.447 P = .002). The nomogram obtained from the stepwise regression model was based on the CD68+/CD8+ ratio, SSTR2 score, and the persistence of postsurgery residual tumor and was able to predict the response to fg-SRLs with good accuracy (area under the curve 0.85).

CONCLUSION

Although our predictive model should be validated in prospective studies, our data suggest that this nomogram may represent an easy to use tool for predicting the fg-SRL outcome early.

A Study of Alternative TrkA Splicing Identifies TrkAIII as a Novel Potentially Targetable Participant in PitNET Progression

Pituitary neuroendocrine tumors (PitNETs) are generally benign but comprise an aggressive, invasive, therapy-resistant, metastatic subset, underpinning a need for novel therapeutic targets. PitNETs exhibit low mutation rates but are associated with conditions linked to alternative splicing, an alternative oncogene pathway activation mechanism. PitNETs express the neurotrophin receptor TrkA, which exhibits oncogenic alternative TrkAIII splicing in other neuroendocrine tumors. We, therefore, assessed whether TrkAIII splicing represents a potential oncogenic participant in PitNETs. TrkAIII splicing was RT-PCR assessed in 53 PitNETs and TrkA isoform(s) expression and activation were assessed by confocal immunofluorescence. TrkAIII splicing was also compared to HIF1α, HIF2α, SF3B1, SRSF2, U2AF1, and JCPyV large T antigen mRNA expression, Xbp1 splicing, and SF3B1 mutation. TrkAIII splicing was detected in all invasive and most non-invasive PitNETs and was significantly elevated in invasive cases. In PitNET lineages, TrkAIII splicing was significantly elevated in invasive PIT1 PitNETs and high in invasive and non-invasive SF1 and TPIT lineages. Immunoreactivity consistent with TrkAIII activation characterized PitNET expressing TrkAIII mRNA, and invasive Pit1 PitNETs exhibited elevated HIF2α expression. TrkAIII splicing did not associate with SF3B1 mutations, altered SF3B1, SRSF2, and U2AF1 or JCPyV large T antigen expression, or Xbp1 splicing. Therefore, TrkAIII splicing is common in PitNETs, is elevated in invasive, especially PIT1 tumors, can result in intracellular TrkAIII activation, and may involve hypoxia. The data support a role for TrkAIII splicing in PitNET pathogenesis and progression and identify TrkAIII as a novel potential target in refractory PitNETs.

Clinical and Molecular Characteristics of Gonadotroph Pituitary Tumors According to the WHO Classification

Since 2017, hormone-negative pituitary neuroendocrine tumors expressing the steroidogenic factor SF1 have been recognized as gonadotroph tumors (GnPT) but have been poorly studied. To further characterize their bio-clinical spectrum, 54 GnPT defined by immunostaining for FSH and/or LH (group 1, n = 41) or SF1 only (group 2, n = 13) were compared and studied for SF1, βFSH, βLH, CCNA2, CCNB1, CCND1, caspase 3, D2R, and AIP gene expression by qRT-PCR. Immunohistochemistry for AIP and/or D2R was performed in representative cases. Overall, patients were significantly younger in group 1 (P = 0.040 vs group 2), with a similar trend excluding recurrent cases (P = 0.078), and no significant difference in gender, tumor size, invasion or Ki67. SF1 expression was similar in both groups but negatively correlated with the patient's age (P = 0.013) and positively correlated with βLH (P < 0.001) expression. Beta-FSH and AIP were significantly higher in group 1 (P = 0.042 and P = 0.024, respectively). Ki67 was unrelated to gonadotroph markers but positively correlated with CCNB1 (P = 0.001) and negatively correlated with CCND1 (P = 0.008). D2R and AIP were strongly correlated with each other (P < 0.001), and both positively correlated with SF1, βFSH, βLH, and CCND1. AIP immunopositivity was frequently observed in both groups, with a similar median score, and unrelated to Ki67. D2R immunostaining was best detected with a polyclonal antibody and mostly cytoplasmic. This study indicates that hormone-negative GnPT tend to occur in older patients but do not significantly differ from other GnPT in terms of invasion or proliferation. It also points out the current limits of D2R immunostaining in such tumors.

Plurihormonal Pituitary Neuroendocrine Tumors: Clinical Relevance of Immunohistochemical Analysis

Plurihormonal pituitary neuroendocrine tumors (PitNETs) are rare forms of tumors that express more than one hormone. The most common association is between growth hormone (GH) and prolactin (PRL), but other unusual combinations have been reported, such as GH and ACTH. Usually, the clinical dominance in these cases is related to GH hypersecretion. In these cases, immunohistochemistry (IHC) of transcription factors (TFs) is very useful for an accurate diagnosis. We included 42 patients diagnosed with pituitary neuroendocrine tumors (PitNETs): 37 patients with a confirmed diagnosis of acromegaly, and 5 patients with prolactinomas. All patients underwent transsphenoidal surgical intervention. We correlated the immunohistochemical features of plurihormonal PitNETs with clinical, hormonal, and imaging data. Tumor specimens were histologically and immunohistochemically examined. Based on the 2022 WHO classification, using IHC, 13 patients exhibited positive staining for more than one hormone, while unusual combinations like GH + ACTH and PRL + ACTH were also identified in other cases. Unusual cell combinations that produce hormones unrelated histogenetically, biochemically, or through regulatory mechanisms can appear and may display aggressive behavior, persistent disease, and high recurrence. We have not identified a clear correlation with the prognosis of these rare PitNETs.

Aerobic exercise interventions to address impaired quality of life in patients with pituitary tumors

Patients with pituitary tumors may experience persistent fatigue and reduced physical activity, based on subjective measures after treatment. These symptoms may persist despite gross total resection of their tumors and biochemical normalization of pituitary function. While reduced quality of life has been commonly acknowledged in pituitary tumor patients, there is a lack of studies on what interventions may be best implemented to ameliorate these issues, particularly when hormonal levels have otherwise normalized. Aerobic exercise programs have been previously described to ameliorate symptoms of chronic fatigue and reduced physical capacity across a variety of pathologies in the literature. As such, a prescribed aerobic exercise program may be an underrecognized but potentially impactful intervention to address quality of life in pituitary tumor patients. This review seeks to summarize the existing literature on aerobic exercise interventions in patients with pituitary tumors. In addition, future areas of study are discussed, including tailoring exercise programs to the hormonal status of the patient and incorporating more objective measures in monitoring response to interventions.

Primary Pituitary Carcinoids Do Not Exist: A Reappraisal in the Era of Pituitary Neuroendocrine Tumours

The World Health Organization classification of pituitary tumours, published in 2022, supported a change in the terminology from "pituitary adenoma" to "pituitary neuroendocrine tumour" (PitNET). The neuroendocrine cells represent an integral part of the diffuse neuroendocrine system, including, among others, thyroid C cells, the parathyroid chief cells, and the anterior pituitary. Normal and neoplastic adenohypophyseal neuroendocrine cells have light microscopic, ultrastructural features and an immunoprofile compatible with the neuroendocrine cells and neuroendocrine tumours from other organs. Moreover, neuroendocrine cells of pituitary origin express transcription factors which indicate their cell-lineage origin. Thus, pituitary tumours are now considered as a continuum with other neuroendocrine tumours. PitNETs may occasionally be aggressive. In this context, the term "pituitary carcinoid" has no specific meaning: it either represents a PitNET, or a metastasis to the pituitary gland of a neuroendocrine tumour (NET). An accurate pathological evaluation, combined where necessary with functional radionuclide imaging, can define the origin of the tumour. We recommend that clinicians liaise with patient groups to understand the terminology to define primary tumours of adenohypophyseal cells. It is incumbent upon the responsible clinician to explain the use of the word "tumour" in a given clinical context.

Position statement on the diagnosis and management of acromegaly: The French National Diagnosis and Treatment Protocol (NDTP)

Acromegaly is a rare disease with prevalence of approximately 60 cases per million, slight female predominance and peak onset in adults in the fourth decade. Clinical diagnosis is often delayed by several years due to the slowly progressive onset of symptoms. There are multiple clinical criteria that define acromegaly: dysmorphic syndrome of insidious onset, symptoms related to the pituitary tumor (headaches, visual disorders), general signs (sweating, carpal tunnel syndrome, joint pain, etc.), complications of the disease (musculoskeletal, cardiovascular, pneumological, dental, metabolic comorbidities, thyroid nodules, colonic polyps, etc.) or sometimes clinical signs of associated prolactin hypersecretion (erectile dysfunction in men or cycle disorder in women) or concomitant mass-induced hypopituitarism (fatigue and other symptoms related to pituitary hormone deficiencies). Biological confirmation is based initially on elevated IGF-I and lack of GH suppression on oral glucose tolerance test or an elevated mean GH on repeated measurements. In confirmed cases, imaging by pituitary MRI identifies the causal tumor, to best determine management. In a minority of cases, acromegaly can be linked to a genetic predisposition, especially when it occurs at a young age or in a familial context. The first-line treatment is most often surgical removal of the somatotroph pituitary tumor, either immediately or after transient medical treatment. Medical treatments are most often proposed in patients not controlled by surgical removal. Conformal or stereotactic radiotherapy may be discussed on a case-by-case basis, especially in case of drug inefficacy or poor tolerance. Acromegaly should be managed by a multidisciplinary team, preferably within an expert center such as a reference or skill center for rare pituitary diseases.

Pituitary surgery outcome in patients 75 years and older: a retrospective study

BACKGROUND

As the population ages, the number of elderly patients with an indication for pituitary surgery is rising. Information on the outcome of patients aged over 75 is limited. This study reports a large series assessing the feasibility of surgical resection in this specific age range, focusing on surgical complications and postoperative results.

METHODS

A retrospective cohort study of patients with pituitary adenomas and Rathke's cleft cysts was conducted. All patients were aged 75 years or over and treated by a single expert neurosurgical team. A control population included 2379 younger adult patients operated by the same surgeons during the same period.

RESULTS

Between 2008 and 2022, 155 patients underwent surgery. Indication was based on vision impairment in most patients (79%). Median follow-up was 13 months (range: 3-96). The first surgery was performed with an endoscopic transsellar approach, an extended endonasal transtuberculum approach and a microscopic transcranial approach in 96%, 3%, and 1% of patients, respectively. Single surgery was sufficient to obtain volume control in 97% of patients. From Kaplan-Meier estimates, 2-year and 5-year disease control with a single surgery were 97.3% and 86.2%, respectively. Resection higher than 80% was achieved in 77% of patients. No vision worsening occurred. In acromegaly and Cushing's disease, endocrine remission was obtained in 90% of non-invasive adenomas. Surgical complications were noted in 5% of patients, with 30-day mortality, hematoma, cerebrospinal fluid leak, meningitis, and epistaxis occurring in 0.6%, 0.6%, 1.9%, 0.6%, and 1.3% respectively. New endocrine anterior deficits occurred in only 5%, while no persistent diabetes insipidus was noted. Compared with younger patients, the complication rate was not statistically different.

CONCLUSIONS

Surgery beyond the age of 75, mainly relying on an endoscopic endonasal transsellar approach, is effective and safe, provided that patients are managed in tertiary centers.

Heterogeneity of TPIT expression in ACTH-secreting extra-pituitary neuroendocrine tumors (NETs) supports the existence of different cellular programs in pancreatic and pulmonary NETs

Extra-pituitary ACTH secretion is associated with a variety of neoplastic conditions and may cause the so-called ectopic ACTH-dependent Cushing syndrome (CS). The clarification of the mechanisms of extra-pituitary ACTH expression would provide potential therapeutic targets for this complex and severe disease. In the adenohypophysis, the transcription factor TPIT, co-operating with other molecules, induces POMC expression and ACTH production. However, no data are currently available on the presence and role of TPIT expression in extra-pituitary ACTH-producing neoplasms. This study was designed to explore TPIT expression in a series of pulmonary and pancreatic ACTH-producing tumors, either CS-associated or not. Forty-one extra-pituitary ACTH-producing neuroendocrine tumors (NETs) were included in the study, encompassing 32 NETs of the lung (LuNETs), 7 of the pancreas (PanNETs), and 2 pheochromocytomas. Of these, 9 LuNETs, all PanNETs, and the two pheochromocytomas were CS-associated. For comparison, 6 NETs of the pituitary gland (PitNETs; 3 ACTH-secreting and 3 ACTH-negative) and 35 ACTH-negative extra-pituitary NETs (15 Lu-NETs and 20 PanNETs) were analyzed. Immunohistochemistry with specific anti-TPIT antibodies and quantitative real-time PCR (qRT-PCR) were performed using standard protocols. TPIT expression was completely absent (protein and mRNA) in PanNETs, pheochromocytomas, and all ACTH-negative NETs. In contrast, it was expressed in 16/32 LuNETs, although with lower levels than in PitNETs. No definite relationship was found between immunohistochemistry TPIT expression and NET grade or the presence of Cushing syndrome. This study further highlights the clinical and biological heterogeneity of extra-pituitary ACTH secretion and suggests that the differences between ACTH-secreting PanNETs and LuNETs may mirror distinct molecular mechanisms underlying POMC expression. Our results point towards the recognition of a real corticotroph-like phenotype of ACTH-producing LuNETs, that is not a feature of ACTH-producing PanNETs.

A Case of an Immature PIT1-Lineage Pituitary Neuroendocrine Tumor of the Nasopharynx

Pituitary neuroendocrine tumors (PitNETs) located in the nasopharynx are a rare occurrence. This case report highlights a case of a 64-year-old female diagnosed with a PitNET incidentally found in her nasopharynx. The tumor was initially seen on MRI, excised, and analyzed with immunohistochemistry, ultimately confirming an immature pituitary-specific positive transcription factor 1 (PIT1)-positive-lineage pituitary neuroendocrine tumor. The tumor contained thyrotropes, somatotrophs, and lactotrophs expressing thyroid stimulating hormone, growth hormone, and prolactin, respectively. These tumors have the potential to exhibit aggressive behavior and can disrupt the surrounding tissue. Furthermore, they can be clinically silent or, conversely, secrete multiple hormones, causing hyperthyroidism, hyperprolactinemia, and acromegaly. For these reasons, they are deemed high risk. Treatment includes surgical excision with or without anti-hormone medications prior to surgery. Medications such as somatostatin analogs are used to decrease tumor size and reduce excessive hormone excretion.

Prognostic Models in Growth-Hormone- and Prolactin-Secreting Pituitary Neuroendocrine Tumors: A Systematic Review

Growth-hormone (GH)- and prolactin (PRL)-secreting PitNETs (pituitary neuroendocrine tumors) are divided into multiple histological subtypes, which determine their clinical and biological variable behavior. Proliferation markers alone have a questionable degree of prediction, so we try to identify validated prognostic models as accurately as possible. (1) Background: The data available so far show that the use of staging and clinical-pathological classification of PitNETs, along with imaging, are useful in predicting the evolution of these tumors. So far, there is no consensus for certain markers that could predict tumor evolution. The application of the WHO (World Health Organisation) classification in practice needs to be further evaluated and validated. (2) Methods: We performed the CRD42023401959 protocol in Prospero with a systematic literature search in PubMed and Web of Science databases and included original full-text articles (randomized control trials and clinical trials) from the last 10 years, published in English, and the search used the following keywords: (i) pituitary adenoma AND (prognosis OR outcome OR prediction), (ii) growth hormone pituitary adenoma AND (prognosis OR outcome OR prediction), (iii) prolactin pituitary adenoma AND (prognosis OR outcome OR prediction); (iv) mammosomatotroph adenoma AND (prognosis OR outcome OR prediction). (3) Results: Two researchers extracted the articles of interest and if any disagreements occurred in the selection process, these were settled by a third reviewer. The articles were then assessed using the ROBIS bias assessment and 75 articles were included. (4) Conclusions: the clinical-pathological classification along with factors such as GH, IGF-1, prolactin levels both preoperatively and postoperatively offer valuable information.

Multidisciplinary management of difficult/aggressive growth-hormone pituitary neuro-endocrine tumors

Growth Hormone-secreting adenomas exhibits variable biological behavior and heterogeneous natural history, ranging from small adenomas and mild disease, to invasive and aggressive neoplasms with more severe clinical picture. Patients not cured or controlled after neurosurgical and first-generation somatostatin receptor ligands (SRL) therapy could require multiple surgical, medical and/or radiation treatments to achieve disease control. To date, no clinical, laboratory, histopathological, or neuroradiological markers are able to define the aggressiveness or predict the disease prognosis in patients with acromegaly. Therefore, the management of these patients requires careful evaluation of laboratory assessments, diagnostic criteria, neuroradiology examinations, and neurosurgical approaches to choose an effective and patient-tailored medical therapy. A multidisciplinary approach is particularly useful in difficult/aggressive acromegaly to schedule multimodal treatment, which includes radiation therapy, chemotherapy with temozolomide and other, recent emerging treatments. Herein, we describe the role of the different members of the multidisciplinary team according to our personal experience; a flow-chart for the therapeutic approach of difficult/aggressive acromegaly patients is proposed.

Development of a cost-effective diagnostic algorithm incorporating transcription factor immunohistochemistry in the evaluation of pituitary tumours

PURPOSE

To determine the utility of the 2022 WHO Classification of pituitary tumours in routine clinical practice and to develop an optimal diagnostic algorithm for evaluation of tumour type in a real-world setting.

METHODS

Retrospective evaluation of pituitary tumour immunohistochemistry (IHC), operatively managed at St Vincent's Hospital Sydney, between 2019 and 2021. Routine IHC comprised evaluation of transcription factors [steroidogenic factor 1 (SF1), T-box transcription factor 19 (TPIT) and pituitary-specific positive transcription factor (PIT1)] and anterior pituitary hormones. Three tiered algorithms were tested, in which hormone IHC was performed selectively based on the initial transcription factor results. These were applied retrospectively and compared with current practice 'gold standard' comprising all transcription factor and hormone IHC. Diagnostic accuracy and cost were evaluated for each.

RESULTS

There were 113 tumours included in the analysis. All three algorithms resulted in 100% concordance with the 'gold standard' in the characterisation of tumour lineage. While all three were associated with relative cost reduction, Algorithm #3, which omitted hormone IHC in the setting of positive SF1 or TPIT and performed IHC for growth hormone, prolactin and thyroid stimulating hormone only in the setting of PIT1 positivity, was the most cost-efficient. Additionally, there were 12/113 tumours with no distinct cell lineage.

CONCLUSION

A diagnostic algorithm omitting hormone IHC except in cases of PIT1 positivity is an accurate and cost-effective approach to diagnose the type of pituitary tumour. A significant subgroup of pituitary tumours with no distinct cell lineage, frequently plurihormonal, remains difficult to classify with the new WHO criteria and requires further evaluation.

Alternative Lengthening of Telomeres (ALT) and Telomerase Reverse Transcriptase Promoter Methylation in Recurrent Adult and Primary Pediatric Pituitary Neuroendocrine Tumors

Neoplastic cells acquire the ability to proliferate endlessly by maintaining telomeres via telomerase, or alternative lengthening of telomeres (ALT). The role of telomere maintenance in pituitary neuroendocrine tumors (PitNETs) has yet to be thoroughly investigated. We analyzed surgical samples of 24 adult recurrent PitNETs (including onset and relapses for 14 of them) and 12 pediatric primary PitNETs. The presence of ALT was assessed using telomere-specific fluorescence in situ hybridization, methylation of telomerase reverse transcriptase promoter (TERTp) by methylation-specific PCR, and ATRX expression by immunohistochemistry. Among the adult recurrent PitNETs, we identified 3/24 (12.5%) ALT-positive cases. ALT was present from the onset and maintained in subsequent relapses, suggesting that this mechanism occurs early in tumorigenesis and is stable during progression. ATRX loss was only seen in one ALT-positive case. Noteworthy, ALT was observed in 3 out of 5 aggressive PitNETs, including two aggressive corticotroph tumors, eventually leading to patient's death. ALT-negative tumors (87.5%) were classified according to their low (29.2%), medium (50%), and high (8.3%) telomere fluorescence intensity, with no significant differences emerging in their molecular, clinical, or pathological characteristics. TERTp methylation was found in 6/24 cases (25%), with a total concordance in methylation status between onset and recurrences, suggesting that this mechanism remains stable throughout disease progression. TERTp methylation did not influence telomere length. In the pediatric cohort of PitNETs, TERTp methylation was also observed in 4/12 cases (33.3%), but no case of ALT activation was observed. In conclusion, ALT is triggered at onset and maintained during tumor progression in a subset of adult PitNETs, suggesting that it could be used for clinical purposes, as a potential predictor of aggressive behavior.

Overview of the 2022 WHO Classification of Pituitary Adenomas/Pituitary Neuroendocrine Tumors: Clinical Practices, Controversies, and Perspectives

The latest edition of the WHO classification of the central nervous system was published in 2021. This review summarizes the major revisions to the classification of anterior pituitary tumors. The most important revision involves preferring the terminology of pituitary neuroendocrine tumor (PitNET), even though the terminology of pituitary adenoma (PA) still can be used according to this WHO classification compared to the previous one. Moreover, immunohistochemistry (IHC) examination of pituitary-specific transcription factors (TFs), including PIT1, TPIT, SF-1, GATA2/3, and ERα, is endorsed to determine the tumor cell lineage and to facilitate the classification of PitNET/PA subgroups. However, TF-negative IHC staining indicates PitNET/PA with no distinct cell lineages, which includes unclassified plurihormonal (PH) tumors and null cell (NC) tumors in this edition. The new WHO classification of PitNET/PA has incorporated tremendous advances in the understanding of the cytogenesis and pathogenesis of pituitary tumors. However, due to the shortcomings of the technology used in the diagnosis of PitNET/PA and the limited understanding of the tumorigenesis of PitNET/PA, the application of this new classification system in practice should be further evaluated and validated. Besides providing information for deciding the follow-up plans and adjunctive treatment after surgery, this classification system offers no additional help for neurosurgeons in clinical practice, especially in determining the treatment strategies. Therefore, it is necessary for neurosurgeons to establish a comprehensive pituitary classification system for PitNET/PA that incorporates neuroimaging grading data or direct observation of invasiveness during operation or the predictor of prognosis, as well as pathological diagnosis, thereby distinguishing the invasiveness of the tumor and facilitating neurosurgeons to decide on the treatment strategies and follow-up plans as well as adjunctive treatment after surgery.

Integrated proteogenomic characterization across major histological types of pituitary neuroendocrine tumors

Pituitary neuroendocrine tumor (PitNET) is one of the most common intracranial tumors. Due to its extensive tumor heterogeneity and the lack of high-quality tissues for biomarker discovery, the causative molecular mechanisms are far from being fully defined. Therefore, more studies are needed to improve the current clinicopathological classification system, and advanced treatment strategies such as targeted therapy and immunotherapy are yet to be explored. Here, we performed the largest integrative genomics, transcriptomics, proteomics, and phosphoproteomics analysis reported to date for a cohort of 200 PitNET patients. Genomics data indicate that GNAS copy number gain can serve as a reliable diagnostic marker for hyperproliferation of the PIT1 lineage. Proteomics-based classification of PitNETs identified 7 clusters, among which, tumors overexpressing epithelial-mesenchymal transition (EMT) markers clustered into a more invasive subgroup. Further analysis identified potential therapeutic targets, including CDK6, TWIST1, EGFR, and VEGFR2, for different clusters. Immune subtyping to explore the potential for application of immunotherapy in PitNET identified an association between alterations in the JAK1-STAT1-PDL1 axis and immune exhaustion, and between changes in the JAK3-STAT6-FOS/JUN axis and immune infiltration. These identified molecular markers and alternations in various clusters/subtypes were further confirmed in an independent cohort of 750 PitNET patients. This proteogenomic analysis across traditional histological boundaries improves our current understanding of PitNET pathophysiology and suggests novel therapeutic targets and strategies.

A Prognostic Risk Model of a Novel Oxidative Stress-Related Signature Predicts Clinical Prognosis and Demonstrates Immune Relevancy in Lung Adenocarcinoma

Lung adenocarcinoma (LUAD) is among the most prevalent malignant lung cancers with a poor prognosis due to high invasiveness and lethality despite multiple treatments. Since the lung is an important organ associated with oxidative stress, and it has been confirmed that oxidative stress represents a potential cancer-specific depletion, it is of important significance to investigate and evaluate the clinical value of oxidative stress mechanisms regulating tumor cell apoptosis. Furthermore, there are few studies on the impact of the microenvironment on reaction to immune-checkpoint inhibitors (ICIs) in patients with LUAD. Based on the TCGA-LUAD dataset, which is stratified into a training set as well as a validation set in a ratio of 2 : 1, this investigation constructs and validates a prognostic predictive power of a gene signature model of oxidative stress-related prognostic signatures. To ascertain the differences between the high-risk score group and the low-risk score group in tumor-infiltrating lymphocytes and patients' response to ICI therapy. This oxidative stress-related prognostic gene signature is composed of MAP3K19 and NTSR1 and is an independent prognosis-related factor in the LUAD group. The outcome of patients having a low risk score is better, and the difference was statistically significant, and individuals with a low risk score had a larger number of infiltrating immune cell distribution in the tumor microenvironment, which was closely related to clinical outcome. Our study suggests that the synergistic effect of oxidative stress-related prognostic gene markers-MAP3K19 and NTSR1 has clinical significance in the prognosis identification and immunotherapy of LUAD patients. Thus, the results may help to better intersect the oxidative stress-related mechanisms in clinical value in LUAD but requires prospective validation.

Recommendations for the diagnosis and radiological follow-up of pituitary neuroendocrine tumours

Pituitary neuroendocrine tumours (PitNETs) constitute a heterogeneous group of tumours with a gradually increasing incidence, partly accounted for by more sensitive imaging techniques and more extensive experience in neuroradiology in this regard. Although most PitNETs are indolent, some exhibit aggressive behaviour, and recurrence may be seen after surgical removal. The changes introduced in the WHO classification in 2017 and terminological debates in relation to neuroendocrine tumours warrant an update of the guidelines for the diagnosis, preoperative and postoperative management, and follow-up of response to treatment of PitNETs. This multidisciplinary document, an initiative of the Neuroendocrinology area of the Sociedad Española de Endocrinología y Nutrición [Spanish Society of Endocrinology and Nutrition] (SEEN), focuses on neuroimaging studies for the diagnosis, prognosis and follow-up of PitNETs. The basic requirements and elements that should be covered by magnetic resonance imaging are described, and a minimum radiology report to aid clinicians in treatment decision-making is proposed. This work supplements the consensus between the Neuroendocrinology area of the SEEN and the Sociedad Española de Anatomía Patológica [Spanish Society of Pathology] (SEAP) for the pathological study of PitNETs.

Clinical and radiological presentation of parasellar ectopic pituitary adenomas: case series and systematic review of the literature

PURPOSE

Parasellar ectopic pituitary adenomas (pEPAs) are extremely rare tumors located out of the sella turcica. PEPAs are heterogeneous entities in terms of anatomical localization and secretion of anterior pituitary hormones.

METHODS

Multicenter retrospective study. Clinical charts' consultation of patients diagnosed with parasellar lesions, to identify all subjects fulfilling the diagnostic criteria of parasellar EPAs. Systematic review of the literature focused on the medical management of prolactin-secreting pEPAs and on the prevalence of radiological bone invasion in pEPAs.

RESULTS

We identified four cases of pEPAs: (1) 54-year-old female with a prolactin-secreting suprasellar EPA successfully treated with cabergoline; (2) 74-year-old male with a non-functioning EPA of the sphenoidal sinus treated with endoscopic transsphenoidal surgery; (3) 75-year-old female with a giant lesion of the skull base (maximum diameter 7.2 cm) diagnosed as a non-functioning EPA after biopsy; (4) 49-year-old male with a silent corticotroph EPA of the sphenoidal sinus and clivus. Three out of four cases had radiological evidence of invasion of the surrounding bone structures. A systematic review of the literature highlighted that medical therapy can be effective in prolactin-secreting pEPAs. Overall, we found mention of local invasiveness in 65/147 cases (44.2%), confirmed by radiological signs of bone invasion/erosion.

CONCLUSION

Our experience confirms the heterogeneity of pEPAs in terms of clinical and radiological presentation, as well as hormone secretion. PEPAs show a high frequency of radiological bone invasion, though similar to that of sellar pituitary adenomas. Although extremely rare, pEPAs need to be considered in the differential diagnosis of parasellar lesions.

Aggressive nonfunctioning pituitary neuroendocrine tumors

Nonfunctioning pituitary neuroendocrine tumors (NF-PitNETs) are tumors that are not associated with clinical evidence of hormonal hypersecretion. According to the World Health Organization (WHO), there are some subtypes of PitNETs that exhibit more aggressive behavior than others. Among the types of potentially aggressive PitNETs, three are nonfunctional: silent sparsely granulated somatotropinomas, silent corticotropinomas, and poorly differentiated PIT-1 lineage tumors. Several biological markers have been investigated in NF-PitNETs. However, there is no single biomarker able to independently predict aggressive behavior in NF-PitNETs. Thus, a more complex and multidisciplinary proposal of a comprehensive definition of aggressive NF-PitNETs is necessary. Here, we suggest a combined and more complete criterion for the NF-PitNETs classification. We propose that aggressiveness is due to a multifactorial combination, and we emphasize the need to include new emerging markers that are involved in the aggressiveness of NF-PitNETs and the need to identify.

High-risk pituitary adenomas and strategies for predicting response to treatment

High-risk pituitary adenomas are aggressive. They show clinical and imaging features similar to those of carcinomas, including infiltration of the surrounding brain structures, but lack cerebrospinal or systemic metastases. In addition, they display distinct behavior, including tendency for fast growth and frequent recurrences, which are difficult to control. The term "high-risk" adenoma was first introduced in the 4th edition of the World Health Organization Classification of Endocrine Tumors in 2017. Five defined adenoma types belong to this category, including sparsely granulated somatotroph, lactotroph in men, Crooke cell, silent corticotroph, and plurihormonal PIT-1 positive adenomas. The morphological and immunohistochemical characteristics of high-risk adenomas are herein described in detail. In addition, the clinical features and the treatment options are presented. This review focuses on predictive markers assessed by immunohistochemistry, which help clinicians to design the appropriate treatment strategies for high-risk adenomas. Somatostatin receptor status predicts effectiveness of postsurgical treatment with somatostatin analogs, and MGMT expression predicts response to treatment with temozolomide. This comprehensive review presents the clinical and pathological features of high-risk pituitary adenomas, underlines the contribution of immunohistochemistry, and emphasizes the leading role of pathology in the design of optimal clinical management.

Overview of the 2022 WHO Classification of Pituitary Tumors

This review summarizes the changes in the 5th Edition of the WHO Classification of Endocrine and Neuroendocrine Tumors that relate to the pituitary gland. The new classification clearly distinguishes anterior lobe (adenohypophyseal) from posterior lobe (neurohypophyseal) and hypothalamic tumors. Other tumors arising in the sellar region are also discussed. Anterior lobe tumors include (i) well-differentiated adenohypophyseal tumors that are now classified as pituitary neuroendocrine tumors (PitNETs; formerly known as pituitary adenomas), (ii) pituitary blastoma, and (iii) the two types of craniopharyngioma. The new WHO classification provides detailed histological subtyping of a PitNET based on the tumor cell lineage, cell type, and related characteristics. The routine use of immunohistochemistry for pituitary transcription factors (PIT1, TPIT, SF1, GATA3, and ERα) is endorsed in this classification. The major PIT1, TPIT, and SF1 lineage-defined PitNET types and subtypes feature distinct morphologic, molecular, and clinical differences. The "null cell" tumor, which is a diagnosis of exclusion, is reserved for PitNETs with no evidence of adenohypophyseal lineage differentiation. Unlike the 2017 WHO classification, mammosomatotroph and acidophil stem cell tumors represent distinct PIT1-lineage PitNETs. The diagnostic category of PIT1-positive plurihormonal tumor that was introduced in the 2017 WHO classification is replaced by two clinicopathologically distinct PitNETs: the immature PIT1-lineage tumor (formerly known as silent subtype 3 tumor) and the mature plurihormonal PIT1-lineage tumor. Rare unusual plurihormonal tumors feature multi-lineage differentiation. The importance of recognizing multiple synchronous PitNETs is emphasized to avoid misclassification. The term "metastatic PitNET" is advocated to replace the previous terminology "pituitary carcinoma" in order to avoid confusion with neuroendocrine carcinoma (a poorly differentiated epithelial neuroendocrine neoplasm). Subtypes of PitNETs that are associated with a high risk of adverse biology are emphasized within their cell lineage and cell type as well as based on clinical variables. Posterior lobe tumors, the family of pituicyte tumors, include the traditional pituicytoma, the oncocytic form (spindle cell oncocytoma), the granular cell form (granular cell tumor), and the ependymal type (sellar ependymoma). Although these historical terms are entrenched in the literature, they are nonspecific and confusing, such that oncocytic pituicytoma, granular cell pituicytoma, and ependymal pituicytoma are now proposed as more accurate. Tumors with hypothalamic neuronal differentiation are classified as gangliocytomas or neurocytomas based on large and small cell size, respectively. This classification sets the standard for a high degree of sophistication to allow individualized patient management approaches.

Intratumoural spatial distribution of S100B + folliculostellate cells is associated with proliferation and expression of FSH and ERα in gonadotroph tumours

Folliculostellate cells are S100B-expressing cells with numerous functions in the normal anterior pituitary. These cells have also been identified in pituitary neuroendocrine tumours (PitNETs), where their precise role remains elusive. Here, we aimed to build a refined cartography of S100B-expressing cells to characterise their interpatient and intratumoural spatial distribution, and to start identifying their potential functions in PitNETs. High-throughput histological analysis of S100B-stained tumour sections of 54 PitNETs revealed a significant decrease in S100B + cells in PitNETs compared to the normal anterior pituitary. A Ki67 index ≥ 3, a mitosis count > 2/10 per high power fields, and a proliferative status, were all associated with fewer S100B + cells in gonadotroph tumours. Gonadotroph tumours also showed interpatient and intratumoural heterogeneity in the spatial distribution of S100B + cells. The existence of an intratumoural heterogeneity was further confirmed by the incorporation to our spatial analysis of additional markers: Ki67, FSH, LH, ERα and SSTR2. The tumour areas with fewer S100B + cells displayed a higher percentage of Ki67 + cells, whereas strong positive correlations were observed between S100B + , FSH + , and ERα + cells. Such spatial associations suggest that S100B + folliculostellate cells could play a role in gonadotroph tumorigenesis, and may contribute to the maintenance of tumour cells in a low proliferating, FSH + /ERα + differentiated state. Albeit, further in-depth functional studies are required to decipher the mechanisms underlying these spatial associations and to potentially identify a therapeutic use.

Outcome of giant pituitary tumors requiring surgery

OBJECTIVE

The management of giant pituitary tumors is complex, with few publications and recommendations. Consequently, patient's care mainly relies on clinical experience. We report here a first large series of patients with giant pituitary tumors managed by a multidisciplinary expert team, focusing on treatments and outcome.

METHODS

A retrospective cohort study was conducted. Giant pituitary tumors were defined by a main diameter > 40mm. Macroprolactinomas sensitive to dopamine agonists were excluded. All patients were operated by a single neurosurgical team. After surgery, multimodal management was proposed, including hormone replacement, radiotherapy and anti-tumor medical therapies. Outcome was modeled using Kaplan-Meyer representation. A logistic regression model was built to identify the risk factors associated with surgical complications.

RESULTS

63 consecutive patients presented a giant adenoma, most often with visual defects. Patients were operated once, twice or three times in 59%, 40% and 1% of cases respectively, mainly through endoscopic endonasal approach. Giant adenomas included gonadotroph, corticotroph, somatotroph, lactotroph and mixed GH-PRL subtypes in 67%, 14%, 11%, 6% and 2% of patients respectively. Vision improved in 89% of patients with prior visual defects. Severe surgical complications occurred in 11% of patients, mainly for tumors > 50 mm requiring microscopic transcranial approach. Additional radiotherapy was needed for 29% of patients, 3 to 56 months after first surgery. For 6% of patients, Temozolomide treatment was required, 19 to 66 months after first surgery.

CONCLUSIONS

Giant pituitary tumors require multimodal management, with a central role of surgery. Most often, tumor control can be achieved by expert multidisciplinary teams.

Pituitary carcinoma: reclassification and implications in the NET schema

The entity known as pituitary carcinoma has been traditionally defined as a tumor of adenohypophysial cells that metastasizes systemically or craniospinally independent of the histological appearance of the lesion. Reported cases of pituitary carcinoma have clinically and histologically resembled their non-metastatic counterparts that were classified as adenomas; the majority of cases were initially diagnosed as adenomas, and with tumor progression and spread, the diagnosis was changed to carcinoma. This classification has been challenged since the definition of malignancy in most organs is not based only on metastatic spread. The extent of local invasion resulting in an inability to completely resect an adenohypophysial tumor can have serious consequences that can cause harm and are therefore not benign. To address this dilemma, it was proposed that pituitary tumors be classified as neuroendocrine tumors. This change in nomenclature is totally appropriate since these tumors are composed of classical neuroendocrine cells; as with other neuroendocrine tumors, they have variable behavior that can be indolent but can involve metastasis. With the new nomenclature, there is no requirement for a distinction between adenomas and carcinomas. Moreover, the WHO/IARC has provided an overarching classification for neuroendocrine neoplasms at all body sites; in this new classification, the term 'neuroendocrine carcinoma' is reserved for poorly differentiated high-grade malignancies that are clinically, morphologically and genetically distinct from well-differentiated neuroendocrine tumors. It remains to be determined if there are true pituitary neuroendocrine carcinomas.

[Algorithm for morphological diagnosis of neoplasms in the chiasmal-sellar region]

In the Turkish saddle area, there is a wide variety of pathological processes, the vast majority of which present as tumors of various origins (up to 90%). For a clear morphological verification of the diagnosis, it is proposed to use a diagnostic algorithm that includes the stages of differential diagnosis of normal adenohypophysis and neurohypophysis with tumors in the anterior and posterior lobes of the pituitary gland, non-pituitary origin neoplasms, as well as with non-tumor pathological processes (inflammation, cystic masses, and hyperplasia). For morphological diagnosis, histochemical and immunohistochemical methods are recommended using various staining techniques (silver impregnation, periodic acid Schiff reaction) of tissue specimens and antibody panels (pituitary hormones, low-molecular cytokeratins, pituitary transcription factors, neuroendocrine markers, etc.).

Clinical Relevance of New World Health Organization Classification System for Pituitary Adenomas: A Validation Study With 2-Year Experience

Background

The new World Health Organization (WHO) classification system proposed a cell lineage-based classification scheme for pituitary adenomas in which transcription factors (TFs) play a major role as key classifiers. We aimed to evaluate clinical relevance of the new classification system in a clinical setting.

Methods

TF staining was retrospectively performed for 153 clinically and histologically well characterized pituitary adenomas. Then, 484 pituitary adenomas were prospectively stained for TFs and then for relevant pituitary hormones. TF and hormone stain-based diagnoses were compared, and differences in clinical manifestations were evaluated.

Results

The accuracies of antibodies for three TFs were successfully validated and had an overall matching rate was 89.6%. We identified 50 (10.4%) cases with discrepancies between TF and pituitary hormone stains. Gonadotroph adenomas lacking follicle-stimulating hormone and luteinizing hormone stains account for most discrepancies. Null cell adenomas may be more prevalent than reported and may be clinically more aggressive than gonadotroph adenomas.

Conclusion

The new WHO classification is mostly well matched with the traditional classification. However, until the new classification is further validated and interpreted in the context of long-term clinical outcomes, routine histological examination should include full slate of immunostains for pituitary hormones as well as TFs.

[Recommendations on the pathological report of pituitary tumors. A consensus of experts of the Spanish Society of Endocrinology and Nutrition and the Spanish Society of Pathology]

Pituitary neuroendocrine tumors (PitNETs) constitute, together with other tumors of the sellar region, 15-25% of intracranial neoplasms. In 2017, the World Health Organization proposed a new classification of PitNETs. The main innovation with respect to the 2004 classification was the recommendation to include in the immunohistochemical evaluation of PitNETs the determination of the transcription factors of the 3 pituitary cell lineages: Pit-1, Tpit and SF-1. Additionally, other clinicopathological classifications with a predictive capacity of tumor behavior during follow-up were proposed. Given these changes, it is appropriate to adapt the knowledge generated during the last 15 years to the daily practice of the treatment and monitoring of PitNETs at the Centers of Excellence in Pituitary Pathology. This document includes the positioning of the Spanish Society of Endocrinology and Nutrition (SEEN) and the Spanish Society of Pathology (SEAP) on the classification and denomination of the PitNETs and the information that the pathologist should provide to the clinician to facilitate the treatment and monitoring of these tumors.

Molecular, functional, and histopathological classification of the pituitary neuroendocrine neoplasms

In 2017, WHO published an updated classification of the pituitary adenomas according to the lineages defined by the transcription factors, PIT1, SF1 and TPIT. Nomenclature of the pituitary tumors follows the mature cell types such as somatotroph (GH), lactotroph (LH), thyrotroph, corticotroph, and gonadotroph (FSH, LH). Null cell adenomas are defined by the absence of expression of any hormones and transcription factors. Not infrequently, the pituitary adenomas are invasive to the adjacent structures and are designated as aggressive adenomas. Knosp grading is often used to define the aggressiveness of the tumor. Sparsely granulated somatotroph adenomas and Crooke cell corticotroph adenomas are representative aggressive adenomas. Recently, genomics regarding various adenomas have been clarified, such as GNAS for somatotrophs and USP8 for corticotrophs. Familial pituitary adenomas are another aspect which has been clarified such as MEN1, Carney's complex, familial isolated pituitary adenoma and McCune-Albright syndrome. The pituitary adenomas often produce GH or PRL, hormones of PIT1 transcription factor. It has been agreed that the pituitary adenomas share the characteristics of neuroendocrine neoplasms. The terminology of pituitary neuroendocrine tumor has been discussed. This review article covers various aspects of pituitary adenomas.

Preoperative prediction of granulation pattern subtypes in GH-secreting pituitary adenomas

OBJECTIVE

The aim of this study was to establish a preoperative prediction method for sparsely granulated (SG) growth hormone (GH)-secreting pituitary adenoma, an aggressive tumour subtype with high recurrence risk, in acromegaly patients.

METHODS

Eighty-three patients with GH-secreting pituitary adenomas were included in this study. GH measurements, cytokeratin immunostaining and electron microscopy were performed to detect granulation patterns. Preoperative factors, including general, radiological and endocrinological features and acute octreotide suppression test outcomes, were compared between SG and densely granulated (DG) groups. The predictive capabilities of these features were analysed using a receiver operating characteristic (ROC) curve, and the most predictive features were combined to establish a grading scale.

RESULTS

Thirty-nine of the 83 patients had SG GH-secreting pituitary adenomas; 44 had DG tumours. SG tumours tended to occur in younger patients and have larger diameters and volumes, higher Knosp grades, lower GH indexes and normalized insulin-like growth factor-1 (IGF-1) level, and a lower ∆GH% after octreotide treatment. The tumour size, Knosp grade, GH index and ∆GH% after octreotide treatment had good predictive performance, with area under the curve (AUC) values ranging from 0.70 to 0.80. Combining four parameters, including diameter, Knosp grade, GH index and ∆GH% after octreotide treatment, we established a grading scale for predicting SG GH-secreting pituitary adenomas with an AUC of 0.84 and relatively high sensitivity and specificity.

CONCLUSIONS

We propose a predictive method for distinguishing SG and DG GH-secreting pituitary adenomas preoperatively. This method will help physicians identify candidates for presurgical medical treatment and neurosurgeons determine radical surgical strategies for high-risk tumours.

Recommendations on the pathological report of pituitary tumors. A consensus of experts of the Spanish Society of Endocrinology and Nutrition and the Spanish Society of Pathology

Pituitary neuroendocrine tumors (PitNETs) constitute, together with other tumors of the sellar region, 15-25% of intracranial neoplasms. In 2017, the World Health Organization proposed a new classification of PitNETs. The main innovation with respect to the 2004 classification was the recommendation to include in the immunohistochemical evaluation of PitNETs the determination of the transcription factors of the 3 pituitary cell lineages: Pit-1, Tpit and SF-1. Additionally, other clinicopathological classifications with a predictive capacity of tumor behavior during follow-up were proposed. Given these changes, it is appropriate to adapt the knowledge generated during the last 15 years to the daily practice of the treatment and monitoring of PitNETs at the Centers of Excellence in Pituitary Pathology. This document includes the positioning of the Spanish Society of Endocrinology and Nutrition (SEEN) and the Spanish Society of Pathology (SEAP) on the classification and denomination of the PitNETs and the information that the pathologist should provide to the clinician to facilitate the treatment and monitoring of these tumors.

The Role of T-box Transcription Factor in a Pituitary Adenoma Diagnostic Algorithm

CONTEXT.—

We previously examined pituitary adenomas with immunohistochemical (IHC) stains for steroidogenic factor 1, Pit-1, anterior pituitary hormones, cytokeratin CAM 5.2, and the α-subunit of human chorionic gonadotropin and found that a screening panel comprising stains for steroidogenic factor 1, Pit-1, and adrenocorticotropic hormone successfully classified most cases and reduced the overall number of stains required.

OBJECTIVES.—

To examine the potential role of IHC stain for T-box transcription factor (Tpit) in the classification of our series of pituitary adenomas and to update our screening panel as necessary.

DESIGN.—

We collected 157 pituitary adenomas from 2 institutions and included these in tissue microarrays. Immunostains for Tpit were scored in a blinded fashion using the Allred system. Adenomas were assigned to a gold standard class based on IHC pattern followed by application of available clinical and serologic information. Test characteristics were calculated. Correlation analyses, cluster analyses, and classification tree analyses were used to see whether IHC staining patterns reliably reflected adenoma class.

RESULTS.—

Of the cases collected, 147 (93.6%) had sufficient material for Tpit analysis. IHC stain for Tpit identified 8 null cell adenomas (all nonfunctioning clinically) as silent corticotrophs; Tpit stains showed better sensitivity, specificity, positive predictive value, and negative predictive value than IHC for adrenocorticotropic hormone and cytokeratin CAM 5.2. Correlation analyses continued to show the expected relationships among IHC stains. Cluster analyses showed grouping of adenomas into clinically consistent groups. Classification tree analysis underscored the central role of transcription factor IHC stains, including Tpit, in adenoma classification.

CONCLUSIONS.—

Substitution of Tpit stain for the adrenocorticotropic hormone stain improves our prior algorithm by reducing the number of false-negatives and false-positives. As a result, fewer adenomas are classified as null cell adenoma, and more adenomas are classified as silent corticotroph adenoma.

Cytokeratin 8/18-negative somatotroph pituitary neuroendocrine tumours (PitNETs, adenomas) show variable morphological features and do not represent a clinicopathologically distinct entity

AIMS

In somatotroph pituitary neuroendocrine tumours (adenomas), a pattern of cytokeratin (CK) 18 expression is used for tumour subclassification, with possible clinical implications. Rare somatotroph tumours do not express CK 18. We aimed to characterise this subset clinically and histologically.

METHODS AND RESULTS

Clinical and pathological data for the study were derived from a previously published data set of a cohort of 110 patients with acromegaly. Data included serum levels of insulin-like growth factor 1 (IGF1), growth hormone (GH), prolactin and thyroid-stimulating hormone (TSH), tumour diameter, tumour invasion defined by Knosp grade and immunohistochemical data concerning the expression of Ki67, p53, E-cadherin, somatostatin receptor (SSTR)1, SSTR2A, SSTR3, SSTR5 and D2 dopamine receptor. Additional immunohistochemical analysis (AE1/3, CK 8/18, vimentin, neurofilament light chain, internexin-α) was performed. CK 18 was negative in 10 of 110 (9.1%) tumours. One of these tumours was immunoreactive with CK 8/18 antibody, while the remainder expressed only internexin-α intermediate filament in patterns similar to CK 18 (perinuclear fibrous bodies). CK-negative tumours showed no significant differences with respect to biochemical, radiological or pathological features. They showed significantly higher expression of SSTR2A compared to the sparsely granulated subtype and significantly lower expression of E-cadherin compared to the non-sparsely granulated subtypes of tumours. The tumours showed divergent morphology and hormonal expression: two corresponded to densely granulated tumours and three showed co-expression of prolactin and morphology of either mammosomatotroph or somatotroph-lactotroph tumours. Four tumours showed morphology and immunoprofile compatible with plurihormonal Pit1-positive tumours.

CONCLUSIONS

CK-negative somatotroph tumours do not represent a distinct subtype of somatotroph tumours, and can be further subdivided according to their morphology and immunoprofile.

Management of sellar and parasellar tumors becoming symptomatic during pregnancy: a practical algorithm based on multi-center experience and systematic literature review

INTRODUCTION

Sellar/parasellar tumors (SPTs) very rarely become symptomatic during pregnancy. No specific guidelines exist for their management, that is extremely challenging as mother and fetus health can be jeopardized.

MATERIALS AND METHODS

Data of patients with SPTs becoming symptomatic during pregnancy treated at two Italian referral Centers were retrospectively collected. Systematic literature review was also performed.

RESULTS

Our series consisted of 6 cases, 3 meningiomas, 1 ACTH-secreting adenoma, 1 pituicytoma and 1 craniopharyngioma. Mean age at presentation was 33.6 ± 6.0 years. Five patients complained of visual disturbances, associated with headache in one case, that occurred between gestation week (GW) 22 and 34. In 5 cases, pregnancy was uneventful with the delivery of a healthy baby between GW 33 and 35, followed by endoscopic surgical tumor exeresis (n = 4) or proton bean therapy (n = 1). Another patient presented with stigmata typical of Cushing's syndrome and rapidly worsening pre-eclampsia, that required pregnancy interruption and adenomectomy. Based on personal and literature cases, a practical algorithm was proposed to help clinicians dealing with these patients.

CONCLUSIONS

SPTs becoming symptomatic in pregnancy deserve careful monitoring and multidisciplinary management. Overall, wait-and-see approach is suggested, reserving surgery to patients with rapidly progressive/life-threatening situations, significant risk of permanent neurological impairment or malignant lesions.

Pituitary in the Spotlight

The German Society of Endocrinology (DGE) has a long-standing scientific and clinical focus on the pituitary. The pituitary working group 'Arbeitsgemeinschaft Hypophyse' is an interdisciplinary special interest group with a focus on advancing diagnosis and treatment of pituitary conditions. On the occasion of the English publication of the S2K clinical guideline Diagnosis and therapy of clinically hormonally inactive pituitary tumors, we present here a series of 12 articles from internationally renowned authors from inside and outside of Germany.

Recommendations on the pathological report of pituitary tumors. A consensus of experts of the Spanish Society of Endocrinology and Nutrition and the Spanish Society of Pathology

Pituitary neuroendocrine tumors (PitNETs) constitute, together with other tumors of the sellar region, 15-25% of intracranial neoplasms. In 2017, the World Health Organization proposed a new classification of PitNETs. The main innovation with respect to the 2004 classification was the recommendation to include in the immunohistochemical evaluation of PitNETs the determination of the transcription factors of the 3 pituitary cell lineages: Pit-1, Tpit and SF-1. Additionally, other clinicopathological classifications with a predictive capacity of tumor behavior during follow-up were proposed. Given these changes, it is appropriate to adapt the knowledge generated during the last 15 years to the daily practice of the treatment and monitoring of PitNETs at the Centers of Excellence in Pituitary Pathology. This document includes the positioning of the Spanish Society of Endocrinology and Nutrition (SEEN) and the Spanish Society of Pathology (SEAP) on the classification and denomination of the PitNETs and the information that the pathologist should provide to the clinician to facilitate the treatment and monitoring of these tumors.

Predictive and prognostic significance of tumour subtype, SSTR1-5 and e-cadherin expression in a well-defined cohort of patients with acromegaly

In somatotroph pituitary tumours, somatostatin analogue (SSA) therapy outcomes vary throughout the studies. We performed an analysis of cohort of patients with acromegaly from the Czech registry to identify new prognostic and predictive factors. Clinical data of patients were collected, and complex immunohistochemical assessment of tumour samples was performed (SSTR1‐5, dopamine D2 receptor, E‐cadherin, AIP). The study included 110 patients. In 31, SSA treatment outcome was evaluated. Sparsely granulated tumours (SGST) differed from the other subtypes in expression of SSTR2A, SSTR3, SSTR5 and E‐cadherin and occurred more often in young. No other clinical differences were observed. Trouillas grading system showed association with age, tumour size and SSTR2A expression. Factors significantly associated with SSA treatment outcome included age, IGF1 levels, tumour size and expression of E‐cadherin and SSTR2A. In the group of SGST, poor SSA response was observed in younger patients with larger tumours, lower levels of SSTR2A and higher Ki67. We observed no relationship with expression of other proteins including AIP. No predictive value of E‐cadherin was observed when tumour subtype was considered. Multiple additional factors apart from SSTR2A expression can predict treatment outcome in patients with acromegaly.

Clinical, Biological, Radiological Pathological and Immediate Post-Operative Remission of Sparsely and Densely Granulated Corticotroph Pituitary Tumors: A Retrospective Study of a Cohort of 277 Patients With Cushing's Disease

PURPOSE

Cushing's disease is the most common cause of endogenous hypercortisolemia due to a corticotroph pituitary tumor. Up-to-date there is no reliable biomarker of invasiveness among corticotroph tumors, while it is well established in the literature that sparsely granulated somatotroph tumors are characterized by poorer prognosis. The aim of the study was to correlate multiple data including clinical, biochemical, radiological, and pathological findings (including granulation pattern) as well as immediate post-operative remission status among patients operated on due to corticotroph tumors.

METHODS

We enrolled all patients consecutively operated on for planned transsphenoidal neurosurgery due to corticotroph PitNETs in years 2010-2018. We excluded from analysis silent corticotroph tumors, plurihormonal PitNETs, and the Crooke's cell adenomas.

RESULTS

We recorded 348 hormonally active corticotroph PitNETs. The results of the analysis showed the female predominance 79.88% (n = 278), with the mean age of Cushing's disease occurrence 43.27 years of age. The mean time from the first signs and symptoms to the operation was 2 years. The women were diagnosed earlier (20-40 years of age vs. 50-60 years of age among men). We performed a detailed analysis of 277 cases classified by granularity pattern as DG or SG corticotroph PitNETs. Densely granulated tumors (DG) occurred four times more frequently than sparsely granulated (SG) (n = 225 vs. n = 52), at similar age (mean 42.94; median 40 vs. mean 45.46; median 45.5; p = 0.3896), but were characterized by lower Knosp's scale grades (p = 0.0147*), smaller preoperative tumors' volumes measured at MRI, and more commonly exhibited lower Ki-67 labeling index (<3%) (p = 0.0168*). What is more, DG adenomas more frequently achieved an immediate remission status (measured as postoperative cortisol concentration <2 µg/dl; p = 0.0180*), and the mean postoperative cortisol concentration in DG group was lower than in SG group (mean 5.375 µg/dl vs. 10.47 µg/dl; median 2.49 µg/dl vs. 6.52 µg/dl; p = 0.0028**).

CONCLUSIONS

Our study indicates that DG corticotroph adenomas occurred at younger age, more commonly were microadenomas as compared to SG tumors, less frequently had invasive features in comparison to SG corticotroph adenomas (p = 0.0019**), and more commonly achieved an immediate postsurgical hormonal remission (p = 0.0180*). We highlight the need for an accurate differentiation of DG and SG subtypes in the pathomorphological diagnosis of corticotropic tumors, especially in invasive PitNETs.

How to Classify and Define Pituitary Tumors: Recent Advances and Current Controversies

Pituitary tumors are very complex and heterogeneous and have a very wide range of proliferative and aggressive behaviors, and how to define and classify these tumors remains controversial. This review summarizes the epidemiology and progress in the classification and definition of pituitary tumors, as well as controversial issues. Based on the results of radiologic and autopsy studies, the prevalence of pituitary tumors has recently increased significantly. However, the majority of pituitary tumors are incidentally discovered and asymptomatic, and such tumors are called pituitary incidentalomas. Most of these incidentalomas do not induce symptoms, remain stable in size, and do not need treatment. The recent revised classification strategies mainly depend on immunohistochemistry (IHC) to detect pituitary hormones and pituitary transcription factors; therefore, the accuracy of diagnosing pituitary tumors has improved. Although new classification strategies and definitions for pituitary tumors have been presented, there are still some controversies. The term pituitary neuroendocrine tumor (PitNET) was proposed by the International Pituitary Pathology Club, and this terminology can encompass the unpredictable malignant behavior seen in the subset of aggressive pituitary adenomas (PAs). However, some endocrinologists who oppose this change in terminology have argued that the use of tumor in the terminology is misleading, as it gives PAs a harmful connotation when the majority are not aggressive. Such terminology may add new ambiguity to the origin of PAs and unnecessary anxiety and frustration for the majority of patients with benign PAs. The classification of aggressive PAs mainly relies on subjective judgment of clinical behavior and lacks objective biomarkers and unified diagnostic criteria. However, the term "refractory" could more accurately represent the characteristics of these tumors, including their clinical behaviors, radiological features, and pathologic characteristics. Moreover, the diagnostic criteria for refractory PAs are stricter, more objective, and more accurate than those for aggressive PAs. Early identification of patients with these tumors through recognition and increased awareness of the definition of refractory PAs will encourage the early use of aggressive therapeutic strategies.

Gonadotroph tumours with a low SF-1 labelling index are more likely to recur and are associated with enrichment of the PI3K-AKT pathway

AIMS

The gonadotroph tumour (GT) is the most frequently resected pituitary neuroendocrine tumour. Although many symptomatic GT are successfully resected, some recur. We sought to identify histological biomarkers that may predict recurrence and explore biological mechanisms that explain this difference in behaviour.

METHODS

SF-1 immunohistochemistry of 51 GT, a subset belonging to a longitudinal prospective cohort study (n = 25), was reviewed. Four groups were defined: Group 1-recently diagnosed GT (n = 20), Group 2-non-recurrent GT with long-term follow up (n = 11), Group 3-initial resections of GT that recur (n = 7) and Group 4-recurrent GT (n = 13). The percentage of SF-1 immunolabelling in the lowest staining fields (SF-1 labelling index (SLI)) was assessed and RNA sequencing was performed on 5 GT with SLI <80% and 5 GT with SLI >80%.

RESULTS

Diffuse, strong SF-1 immunolabelling was the most frequent pattern in Groups 1/2, whereas patchy SF-1 staining predominated in Groups 3/4. There was a lower median SLI in Groups 3/4 than 1/2. Overall, GT with SLI <80% recurred earlier than GT with SLI >80%. Differential expression analysis identified 89 statistically significant differentially expressed genes (FDR <0.05) including over-expression of pituitary stem cell genes (SOX2, GFRA3) and various oncogenes (e.g. BCL2, ERRB4) in patchy SF-1 GT. Gene set enrichment analysis identified significant enrichment of genes involved in the PI3K-AKT pathway.

CONCLUSIONS

We speculate that patchy SF-1 labelling in GT reflects intratumoural heterogeneity and are less differentiated tumours than diffusely staining GT. SF-1 immunolabelling patterns may have prognostic significance in GT, but confirmatory studies are needed for further validation.

Proposal of a clinically relevant working classification of pituitary neuroendocrine tumors based on pituitary transcription factors

The immunohistochemistry (IHC) characterization of pituitary transcription factors (PTFs) PIT1, TPIT, and SF1, which enable the identification of three different adenohypophyseal cell lines, has been incorporated into the latest classification system of the World Health Organization (WHO) for pituitary adenomas. This change overturns the concept of the adenoma as solely a hormone producer and classifies these tumors based on their cell lineage. The aim of the study was to provide a diagnostic algorithm, based on IHC expression of hypophyseal hormones with potential use in diagnostic practice, contributing to an improved classification of pituitary adenomas. Our sample included 146 pituitary adenomas previously classified based on hormonal subtypes by IHC (former 2004 WHO criteria) and re-evaluated after the IHC quantification of PIT1, TPIT, and SF1 expression, under WHO 2017 recommendations. We assessed the correlation between expression of PTFs and the classification as per hormonal IHC and correlated clinicopathological profiles based on PTFs. The IHC study of PTFs allowed reclassification of 82% of tumors that were negative for all pituitary hormones, with 21 positive cases for SF1 (reclassified as gonadotroph tumors), 1 positive case for TPIT (reclassified as a corticotroph tumor), and 4 positive cases for PIT1. Using SF1 enabled detection of a substantial portion of gonadotroph tumors, reducing the estimated prevalence of null cell tumors to less than 5%, and identification of plurihormonal pituitary neuroendocrine tumors with PIT1-SF1 coexpression and hormone-negative PIT1s, a group in which we did not observe differences in the clinical behavior compared with the rest of the tumors of the same cell lineage.Our results suggest that applying a diagnostic algorithm based on the study of PTFs could contribute to improving the classification of pituitary adenomas. By adding TPIT assessment, we propose a two-step algorithm, with hypophyseal hormones being used in a selective modality, depending on initial results.

Pituitary Gangliocytoma Producing TSH and TRH: A Review of "Gangliocytomas of the Sellar Region"

PURPOSE

Pituitary gangliocytomas (GCs) are rare neuronal tumors that present with endocrinological disorders, such as acromegaly, amenorrhea-galactorrhea syndrome, and Cushing's disease. Most pituitary GCs coexist with pituitary adenomas pathologically and are diagnosed as mixed gangliocytoma-adenomas. Herein, we report a case of 45-year-old man who presented with the syndrome of inappropriate secretion of thyroid-stimulating hormone (SITSH) and discuss the pathogenesis of pituitary GCs.

METHODS

Pituitary magnetic resonance imaging showed an 8-mm homogeneous and poorly enhanced mass inside the pituitary gland. Endoscopic transsphenoidal surgery was performed under a preoperative diagnosis of thyrotroph adenoma. However, the tumor was finally diagnosed as gangliocytoma without an adenomatous component. The tumor was further analyzed via immunohistochemistry and electron microscopy. Additionally, we searched MEDLINE and PubMed for previously published cases of isolated pituitary GCs and analyzed the reported clinicopathological findings.

RESULTS

The patient showed complete clinical and endocrinological recovery after an operation. The tumor was positive for thyrotropin (TSH), TSH-releasing hormone (TRH), Pit-1, GATA-2, and most neuronal markers. Electron microscopy demonstrated the presence of intracytoplasmic secretory granules and neuronal processes. Co-secreting hypothalamic and pituitary hormone inside the tumor indicated autocrine/paracrine endocrinological stimulation.

CONCLUSION

Herein, we report a case of SITSH caused by an isolated pituitary gangliocytoma, expressing both TSH and TRH, which, to our best knowledge, is the first reported case of such a condition. The multidirectional differentiation and multihormonal endocrine characteristics of these tumors indicate that they are a member of neuroendocrine neoplasms, further supporting that they are derived from neural crest cells.

Hyperprolactinemia in Acromegaly is Related to Prolactin Secretion by Somatolactotroph Tumours

The aim of this study is to assess differences in patient characteristics, tumour characteristics and hormone levels between acromegalic patients with and without hyperprolactinemia. 44 patients of the University Hospital of Brussels, Belgium with acromegaly who were diagnosed between January 2007 and July 2018 were included in this study. Nineteen patients were classified in the hyperprolactinemia group and 25 patients were classified in the normoprolactinemia group. No significant differences between acromegalic patients with and without hyperprolactinemia were found in age at diagnosis, gender, presence of hyperprolactinemia symptoms, insulin-like growth factor 1, growth hormone and testosterone levels, tumour volume, tumour invasiveness, immunohistochemistry of growth hormone and prolactin, Ki-67 index and mitotic index. However, for a cut-off of 10% of prolactin-positive cells, there was a trend towards a higher percentage of prolactin-positive tumours in hyperprolactinemia patients (p=0.054) and higher mean prolactin level in case of positive prolactin immunostaining (p=0.007)). In our study there were no differences in characteristics between acromegaly patients with hyper- and normoprolactinemia. An association between the serum prolactin level and the positivity of prolactin immunohistochemistry of the adenoma tissue was found. The absence of a difference in tumour volume between patients with hyper- and normoprolactinemia suggests that the hyperprolactinemia is likely to be caused by the co-secretion of growth hormone and prolactin by the tumour. Finally, for the first time, the cut-off of 10% of prolactin cells was validated for the diagnosis of somatolactotroph tumours in acromegaly.

World Health Ozganization 2017 Classification of Pituitary Tumors

The 2017 (fourth edition) World Health Organization Classification of Endocrine Tumors has recommended major changes in classification of tumors of the pituitary gland and region. In addition to the accurate tumor subtyping, assessment of the tumor proliferative potential (mitotic and/or Ki-67 index) and other clinical parameters such as tumor invasion is strongly recommended in individual cases for consideration of clinically aggressive adenomas. It is expected that this new WHO classification will establish more uniform biologically and clinically groups of pituitary tumors and contribute to understanding of clinical outcomes for patients harboring pituitary tumors.

Aggressive Pituitary Adenomas and Carcinomas

A subset of pituitary tumors present an aggressive behavior that remains difficult to predict, and in rare cases they metastasize. The current European Society for Endocrinology (ESE) guidelines for the management of aggressive pituitary tumors and carcinomas provide valuable guidance, but several issues remain unaddressed because of the scarcity of data in the literature. This article presents key clinical aspects regarding aggressive pituitary tumors and carcinomas, and also discusses some of the unanswered questions of the ESE guidelines, focusing on both diagnosis and treatment.

Immunotherapy in Corticotroph and Lactotroph Aggressive Tumors and Carcinomas: Two Case Reports and a Review of the Literature

Once temozolomide has failed, no other treatment is recommended for pituitary carcinomas and aggressive pituitary tumors. Recently, the use of immune checkpoint inhibitors (ICIs) has raised hope, but so far, only one corticotroph carcinoma and one aggressive corticotroph tumor treated with immunotherapies have been reported in the literature. Here, we present two cases, one corticotroph carcinoma and one aggressive prolactinoma (the first one reported in the literature) treated with ipilimumab (1 mg/kg) and nivolumab (3 mg/kg) every three weeks, followed by maintenance treatment with nivolumab (3 mg/kg every 2 weeks) in the case of the corticotroph carcinoma, and we compare them with the two previously reported cases. Patient #1 presented a biochemical partial response (plasma ACTH decreased from 13,813 to 841 pg/mL) and dissociated radiological response to the combined ipilimumab and nivolumab—the pituitary mass decreased from 37 × 32 × 41 to 29 × 23 × 42 mm, and the pre-existing liver metastases decreased in size (the largest one from 45 to 14 mm) or disappeared, while a new 11-mm liver metastasis appeared. The maintenance nivolumab (21 cycles) resulted in a stable disease for the initial liver metastases, and in progressive disease for the newly appeared metastasis (effectively treated with radiofrequency ablation) and the pituitary mass. Patient #2 presented radiological and biochemical progressive disease after two cycles of ICIs—the pituitary mass increased from 38 × 42 × 26 to 53 × 57 × 44 mm, and the prolactin levels increased from 4410 to 9840 ng/mL. In conclusion, ICIs represent a promising therapeutic option for aggressive pituitary tumors and carcinomas. The identification of subgroups of responders will be key.