Protocol for the examination of specimens from patients with primary pituitary tumors

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.

The Driver Role of Pathologists in Endocrine Oncology: What Clinicians Seek in Pathology Reports

Endocrine neoplasia represents an increasingly broad spectrum of disorders. Endocrine neoplasms range from incidental findings to potentially lethal malignancies. In this paper, we cover the impact of pathology in the interpretation of the clinic-pathological, genetic, and radiographic features underpinning these neoplasms. We highlight the critical role of multidisciplinary interactions in structuring a rational diagnostic and efficient therapeutic plan and emphasize the role of histopathological input in decision-making. In this context, standardized pathology reporting and second opinion endocrine pathology review represent relevant tools to improve the overall diagnostic workup of patients affected by endocrine tumors in every specific scenario. In fact, although a relevant proportion of cases may be correctly identified based on clinical presentation and biochemical/imaging investigations, a subset of cases presents with atypical findings that may lead to an inappropriate diagnosis and treatment plan based on a wrong pathological diagnosis if all pieces of the puzzle are not correctly considered. Pathologists have a responsibility to actively guide clinicians before and during surgical procedures to prevent unnecessary interventions. In all areas of endocrine pathology, pathologists must understand the complexity of tissue preservation and assay sensitivities and specificities to ensure the optimal quality and interpretation of diagnostic material. Finally, pathologists are central actors in tumor tissue biobanking, which is an expanding field in oncology that should be promoted while adhering to strict ethical and methodological standards.

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.

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.).

[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.

Pituitary neuroendocrine tumors: a model for neuroendocrine tumor classification

The classification of adenohypophysial neoplasms as "pituitary neuroendocrine tumors" (PitNETs) was proposed in 2017 to reflect their characteristics as epithelial neuroendocrine neoplasms with a spectrum of clinical behaviors ranging from small indolent lesions to large, locally invasive, unresectable tumors. Tumor growth and hormone hypersecretion cause significant morbidity and mortality in a subset of patients. The proposal was endorsed by a WHO working group that sought to provide a unified approach to neuroendocrine neoplasia in all body sites. We review the features that are characteristic of neuroendocrine cells, the epidemiology and prognosis of these tumors, as well as further refinements in terms used for other pituitary tumors to ensure consistency with the WHO framework. The intense study of PitNETs has provided information about the importance of cellular differentiation in tumor prognosis as a model for neuroendocrine tumors in different locations.

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.

Challenges in the Diagnosis of Pituitary Neuroendocrine Tumors

Detailed analysis of cytodifferentiation and hormone production has classified pituitary neuroendocrine tumors (PitNETs) in a formal system that reflects the lineage differentiation of nontumorous adenohypophysial cells as well as subtypes of tumors that have predictive value. In addition, tumors composed of cells that lack terminal differentiation are well characterized. To comply with the proposal to create an overarching classification of neuroendocrine neoplasia, these tumors are now called PitNETs rather than adenomas. The next important step will be to relinquish the term "pituitary carcinoma" for metastatic PitNETs that remain well differentiated, and to alter the terminology used for tumors that are not terminally differentiated to reflect only their immature lineage. The existence of mixed neuroendocrine and non-neuroendocrine neoplasms (MiNENs) similar to those at other body sites is proven by mixed craniopharyngiomas with PitNETs. As with other NETs, these neoplasms should be reported with synoptic data that guide completeness of reporting. A formal system of grading should be created, but not only based on proliferation, as these tumors have shown the prognostic value of cytodifferentiation. A formal system of staging should also be devised to complement grade in the thorough and accurate diagnosis of tumors that arise from adenohypophysial cells.

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.

Significance of Crooke's Hyaline Change in Nontumorous Corticotrophs of Patients With Cushing Disease

BACKGROUND

Glucocorticoid excess in Cushing disease (CD) leads to negative feedback suppression, resulting in Crooke's hyaline change (CC) of nontumorous pituitary corticotrophs. We aimed to determine the predictive value of CC of nontumorous corticotrophs in CD.

METHODS

The retrospective chart review study included patients with clinical, biochemical, radiologic and outcome data and evaluable histopathology specimens from pituitary surgery for CD. The main outcome was remission of CD, defined by clinical features, biochemical testing, and corticosteroid dependency.

RESULTS

Of 144 CD patients, 60 (50 women, mean age 43.6±14) had clinical follow-up, biochemical data and histopathology specimens that included evaluable nontumorous adenohypophysis. Specimens from 50 patients (83.3%) demonstrated CC in nontumorous corticotrophs, and 10 (16.7%) had no CC (including 3 with corticotroph hyperplasia). One patient with CC was lost to follow-up and one without CC had equivocal outcome results. During a mean (SD) follow-up period of 74.9 months (61.0), recurrent or persistent disease was documented in 18 patients (31.0%), while 40 (69.0%) were in remission. In patients with CC, the remission rate was 73.5% (95% CI, 59.7%-83.7%) (36/49), whereas it was 44.4% (95% CI, 18.9%-73.3%) (4/9) in patients with no CC. The combination of serum cortisol >138 nmol/L within a week of surgery coupled with absence of nontumorous CC greatly improved the prediction of recurrent or persistent disease.

CONCLUSIONS

CC of nontumorous corticotrophs was observed in 83% of patients with CD, and most patients with CC experienced remission. Absence of CC in nontumorous corticotrophs may serve as a predictor of reduced remission in patients with CD.

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.

Epidemiology and biomarker profile of pituitary adenohypophysial tumors

Recent studies have reported the prevalence of pituitary tumors to be ~1/1000 population. Many are prolactin-producing tumors that are managed medically, however, the epidemiology of surgically resected pituitary adenohypophysial neuroendocrine tumors has not been reported in a large series with detailed characterization. We reviewed 1055 adenohypophysial tumors from 1169 transsphenoidal resections from the pathology files of University Health Network, Toronto, 2001-2016. Tumors were characterized by immunohistochemical localization of transcription factors (Pit-1, ERα, SF-1, Tpit), hormones (adrenocorticotropin, growth hormone, prolactin, β-thyrotropin, β-folliculotropin, β-luteotropin, α-subunit), and other biomarkers (keratins, Ki67, p27, FGFR4). Electron microscopy was used only for unusual lesions. In this cohort, 51.3% of patients were female; the average age was 51 years. Gonadotroph tumors represented 42.5%. Pit-1-lineage-tumors represented 29.9%; these were subclassified as growth-hormone-predominant (somatotroph/mammosomatotroph/mixed; 53%), prolactin-predominant (lactotroph/acidophil-stem-cell; 28%), thyrotrophs (2%), plurihormonal (14%), and not-otherwise-specified (3%). Corticotroph tumors represented 17.1%. Only 4.5% were null cell tumors and 0.5% were unusual plurihormonal tumors. In 5.5% the tumor was not characterized for technical reasons (sample size, fixation, necrosis or other artifact). All corticotroph and plurihormonal tumors were positive for keratins; others tumors showed variable negativity with highest rates in gonadotroph (37.1%) and null cell tumors (28.2%). Tumors with a Ki67 ≥ 3% comprised 60% of this cohort. Global loss of p27 was most frequent in corticotroph neoplasms, specifically those associated with elevated glucocorticoid levels. Corticotroph and lactotroph tumors were more common among females; gonadotroph tumors were more common among males. Younger patients had mainly corticotroph and Pit-1-lineage neoplasms, whereas older patients harbored mainly gonadotroph tumors. This represents one of the largest surgical series of morphologically characterized pituitary tumors reported to date and the first to include the routine use of transcription factors for tumor classification. The data provide the basis for clinicopathologic correlations that are helpful for prognostic and predictive patient management.

Both invasiveness and proliferation criteria predict recurrence of non-functioning pituitary macroadenomas after surgery: a retrospective analysis of a monocentric cohort of 120 patients

INTRODUCTION

Additional robust criteria to predict early postoperative recurrence of non-functioning pituitary macroadenomas (NFMAs) are needed. Recently, a new classification of pituitary tumors has been proposed, which is based on both radiological and histological criteria and allows the grading into 5 groups of different potential aggressiveness. The aim of this study was to use this classification to further characterize predictive factors of recurrence in an independent series of NFMA.

CASES AND METHODS

120 patients operated for a NFMA were analyzed retrospectively. For each of them, the invasion of the cavernous and/or sphenoidal sinuses by the tumor was studied on the preoperative MRI and the proliferative character was based on precise histological and immunohistological examination.

RESULTS

26% (n = 31) of the adenomas were proliferative and 57% (n = 68) were invasive. The invasive lesions were larger (P < 0.001) and their removal was complete in only 82% of the cases. The distribution of NFMAs was as follows: 32% grade 1a, 11% (proliferative) grade 1b, 42% (invasive) grade 2a and 15% (proliferative and invasive) grade 2b. Their probability of recurrence at 5 years was 20, 39, 44 and 66%, respectively. A young age, the atypical character and the presence of postoperative residual tumor were all independent risk factors of recurrence (P < 0.025).

DISCUSSION

The new clinicopathological classification proves to be very useful in predicting the risk of recurrence of non-functioning pituitary macroadenomas after a first surgery. In particular, grade 2b lesions showed an overall likelihood of recurrence that was 8.6 times greater than those of grade 1a.

Histological features of pituitary adenomas and sellar region masses

PURPOSE OF REVIEW

Most pituitary region masses are pituitary adenomas; however, when other sellar region masses are encountered by clinicians or pathologists, the differential diagnosis can be broad. This review will focus on updates for pituitary adenomas, as well as briefly discuss some of these other entities: Rathke cleft cyst, hypophysitis, craniopharyngioma, pituicytoma, and spindle cell oncocytoma.

RECENT FINDINGS

The use of new immunohistochemical (IHC) tools for assessing transcription factors, pituitary transcription factor-1, steroidogenic factor-1, and the not-yet-widely available Tpit IHC have provided insights into origin particularly of clinically silent and even hormone-negative pituitary adenomas. IHC for keratins coupled with use of E-cadherin IHC can serve to easily identify sparsely granulated growth hormone adenomas that behave more aggressively and may not respond well to some therapies. Thyroid transcription factor-1 IHC has shown common embryological lineage of pituicytoma, spindle cell oncocytoma, and granular cell tumor of neurohypophysis.

SUMMARY

IHC supplements classification of pituitary adenoma subtypes for clinicians and can confirm diagnosis of nonpituitary adenoma sellar region masses.

Steroidogenic Factor 1, Pit-1, and Adrenocorticotropic Hormone: A Rational Starting Place for the Immunohistochemical Characterization of Pituitary Adenoma

Context.—Pituitary adenoma classification is complex, and diagnostic strategies vary greatly from laboratory to laboratory. No optimal diagnostic algorithm has been defined.

Objective.—To develop a panel of immunohistochemical (IHC) stains that provides the optimal combination of cost, accuracy, and ease of use.

Design.—We examined 136 pituitary adenomas with stains of steroidogenic factor 1 (SF-1), Pit-1, anterior pituitary hormones, cytokeratin CAM5.2, and α subunit of human chorionic gonadotropin. Immunohistochemical staining was scored using the Allred system. Adenomas were assigned to a gold standard class based on IHC results and available clinical and serologic information. Correlation and cluster analyses were used to develop an algorithm for parsimoniously classifying adenomas.

Results.—The algorithm entailed a 1- or 2-step process: (1) a screening step consisting of IHC stains for SF-1, Pit-1, and adrenocorticotropic hormone; and (2) when screening IHC pattern and clinical history were not clearly gonadotrophic (SF-1 positive only), corticotrophic (adrenocorticotropic hormone positive only), or IHC null cell (negative-screening IHC), we subsequently used IHC for prolactin, growth hormone, thyroid-stimulating hormone, and cytokeratin CAM5.2.

Conclusions.—Comparison between diagnoses generated by our algorithm and the gold standard diagnoses showed excellent agreement. When compared with a commonly used panel using 6 IHC for anterior pituitary hormones plus IHC for a low-molecular-weight cytokeratin in certain tumors, our algorithm uses approximately one-third fewer IHC stains and detects gonadotroph adenomas with greater sensitivity.

Growth hormone tumor histological subtypes predict response to surgical and medical therapy

Growth hormone (GH) pituitary tumors are associated with significant morbidity and mortality. Current treatments, including surgery and medical therapy with somatostatin analogs (SSA), dopamine agonists and/or a GH receptor antagonist, result in disease remission in approximately half of patients. Predictors of GH tumor response to different therapies have been incompletely defined based on histologic subtype, particularly densely (DG) versus sparsely (SG) granulated adenomas. The aim of this study was to examine our own institutional experience with GH adenomas and correlate how subtype related to clinical parameters as well as response to surgery and medical therapies. A retrospective chart review of 101 acromegalic patients operated by a single neurosurgeon was performed. Clinical data were correlated with histologic subtype and disease control, as defined by IGF-1 levels, and random growth hormone levels in response to surgery and/or medical therapies. SG tumors, compared to DG, occurred in younger patients (p = 0.0010), were 3-fold larger (p = 0.0030) but showed no differences in tumor-invasion characteristics (p = 0.12). DG tumors had a higher rate of remission in response to surgery compared to SG, 65.7 vs. 14.3 % (p < 0.0001), as well as to medical therapy with SSAs (68.8 % for DG vs. 28.6 % for SG tumors; p = 0.028). SG tumors not controlled with SSAs consistently responded to a switch to, or addition of, a GH receptor antagonist. Histological GH tumor subtyping implicates a different clinical phenotype and biologic behavior, and provides prognostic significance for surgical success and response to medical therapies.

An Algorithmic Approach to Sellar Region Masses

Context

Most sellar region masses (85%–90%) are pituitary adenomas; however, other neoplasms or even inflammatory or cystic nonneoplastic lesions may occasionally be encountered in this location. A practical, non–electron-microscopically based approach is essential for the daily practice of diagnosing and subclassifying adenomatous and nonadenomatous sellar region lesions.

Objective

To provide an algorithmic approach to sellar region masses for the pathologist and to formulate a cost-effective, limited panel of stains and immunostains that can be used in daily practice at most small to medium-sized centers.

Design

Pool collective experience of 3 neuropathologists practicing at academic medical centers with expertise in diagnosis and treatment of sellar region masses to craft a single-page algorithmic diagram and to liberally illustrate the range of lesions present in the sellar region.

Results

After formulating a differential diagnosis, the general pathologist can generate a confident final diagnosis of adenoma using 1 histochemical (reticulin) and 1 immunohistochemical (synaptophysin) stain, supplemented by 5 immunohistochemical stains (CAM5.2, follicle-stimulating hormone, growth hormone, prolactin, and adrenocorticotropic hormone), which provide subtyping of the adenoma in the overwhelming majority of examples. CAM5.2 and clinical information further help identify clinically aggressive variants such as sparsely granulated growth hormone adenomas and silent adrenocorticotropic hormone adenomas, respectively. MIB-1, thyroid transcription factor 1, and S-100 protein can be of further assistance in select cases where increased mitotic activity or possible nonadenomatous spindle cell lesions are suspected.

Conclusions

Adenomas, normal anterior or posterior gland, and nonadenomatous masses can be easily diagnosed in a nontertiary pathology laboratory setting.

A prognostic clinicopathologic classification of pituitary endocrine tumors

Pituitary endocrine tumors are considered as benign. However, clinical and pathological data favor their consideration as more than an endocrinological disease. Using data from a retrospective case-control study of 410 patients, with 8 years of follow-up, the authors have validated a new clinicopathologic classification of pituitary tumors. This classification is based on tumor size, immunohistochemical type, and grade based on the assessment of invasion and proliferation, and it provides a prognostic value for predicting postoperative disease-free outcome or recurrence/progression status. This classification aids the identification of patients presenting with pituitary tumors that have a high risk of recurrence and enable construction of personalized therapies.

Improving differential diagnosis of pituitary adenomas

Pituitary adenomas are common tumors arising in adenohypophysial cells or their precursors. For improving control of the disease an early diagnosis is important. Initially considered sporadic tumors, some of them are associated with familial syndromes and their recognition and classification is also required. Morphologically, pituitary adenomas represent a heterogeneous group of tumors with several subtypes and different clinical behavior thus a precise pathological diagnosis is crucial. The simple diagnosis of pituitary adenoma is not satisfactory and the correct classification of histological subtypes may predict aggressiveness in the majority of cases. Although considered not malignant, some of them are clinically aggressive and their recognition remains a challenge. In this paper we present the recent advances in the event of improving early recognition and differential diagnosis of pituitary tumors.

In search of a prognostic classification of endocrine pituitary tumors

Pituitary tumors, the most frequent intracranial tumors, are historically considered benign. However, various pieces of clinical evidence and recent advances in pathological and molecular data suggest the need to consider that these tumors are more than an endocrinological disease despite the low incidence of metastasis. We present here a historical and critical review of the classifications of pituitary tumors, including a new prognostic clinicopathological classification based on tumor size, immunohistological subtype (prolactin (PRL), growth hormone (GH), follicle-stimulating hormone and luteinizing hormone (FSH-LH), adrenocorticotropic hormone (ACTH), and thyroid-stimulating hormone (TSH)), and five grades, which take into account invasion and proliferation of the tumors. We also present a brief review of the main markers of tumor behavior. We believe that a better classification of these tumors and the identification of prognostic markers will help the clinician to choose the appropriate therapeutic management.

Management of endocrine disease: clinicopathological classification and molecular markers of pituitary tumours for personalized therapeutic strategies

Pituitary tumours, the most frequent intracranial tumour, are historically considered benign. However, various pieces of clinical evidence and recent advances in pathological and molecular analyses suggest the need to consider these tumours as more than an endocrinological disease, despite the low incidence of metastasis. Recently, we proposed a new prognostic clinicopathological classification of these pituitary tumours, according to the tumour size (micro, macro and giant), type (prolactin, GH, FSH/LH, ACTH and TSH) and grade (grade 1a, non-invasive; 1b, non-invasive and proliferative; 2a, invasive; 2b, invasive and proliferative and 3, metastatic). In addition to this classification, numerous molecular prognostic markers have been identified, allowing a better characterisation of tumour behaviour and prognosis. Moreover, clinical and preclinical studies have demonstrated that pituitary tumours could be treated by some chemotherapeutic drugs or new targeted therapies. Our improved classification of these tumours should now allow the identification of prognosis markers and help the clinician to propose personalised therapies to selected patients presenting tumours with a high risk of recurrence.

A history of pituitary pathology

The history of pituitary pathology is a long one that dates back to biblical times, but the last 25 years have represented an era of "coming of age." The role of the pituitary in health and disease was the subject of many studies over the last century. With the development of electron microscopy, immunoassays, and immunohistochemistry, the functional alterations associated with pituitary disease have been clarified. The additional information provided by molecular genetic studies has allowed progress in understanding the pathogenesis of pituitary disorders. Nevertheless, many questions remain to be answered. For example, pathologists cannot morphologically distinguish locally aggressive adenomas from carcinomas when tumor is confined to the sella. Sadly, basal cell carcinoma, the most common carcinoma of skin, usually causes less morbidity than pituitary adenomas, which occur in almost 20 % of the general population, can cause significant illness and even death, and yet are still classified as benign. The opportunity to increase awareness of the impact of these common lesions on quality of life is the current challenge for physicians and patients. We anticipate that ongoing multidisciplinary approaches to pituitary disease research will offer new insights into diseases arising from this fascinating organ.

Therapeutic implications of accurate classification of pituitary adenomas

Recent data suggest that 1 of 5 individuals in the general population is affected with a pituitary adenoma. Many of these neoplasms are clinically non-functioning adenomas that may be small and clinically undetected or may present as mass lesions; others are hormonally active and cause significant morbidity due to the metabolic effects of hormone excess (e.g., acromegaly and cushing's disease). In either case, they can grow and invade adjacent anatomic structures. Tumors with similar clinical features are morphologically heterogenous and detailed comprehensive classification of pituitary adenomas is important to predict specific clinical behaviors and genetic changes that serve as targets for therapy. We provide a practical approach to clinical diagnosis and highlight the pitfalls in the classification of these common neoplasms.

Results of immunohistochemical staining of cell-cycle regulators: the prediction of recurrence of functioning pituitary adenoma

OBJECTIVE

This study was undertaken primarily to investigate the possible prognostic values of several cell-cycle regulators for the prediction of functioning pituitary adenoma (FPA) recurrence after surgical resection by immunohistochemically analyzing tumor samples obtained by surgical resection.

METHODS

The medical records of the patients with FPA diagnosed from January 2000 to December 2009 at the Department of Neurosurgery at Samsung Changwon Hospital and Dong-A University Medical Center were selected. Immunohistochemical staining was performed on archived paraffin-embedded tissues obtained by surgical resection for adenohypophysial cells, cell-cycle regulatory proteins (p16, p15, p21, cyclin-dependent kinase [CDK] 4 and 6, phosphorylated retinoblastoma [pRB] protein, and cyclin D1), MIB-1 antigen, and p53.

RESULTS

Of the 174 FPAs, 62 (35.6%) recurred during follow-up period (mean duration 62.4 months, range 24.2-118.9 months). Immunohistochemically, overstaining for p16 in 89 samples (51.1%), p15 in 27 samples (15.5%), p21 in 20 samples (11.5%), CDK4 in 54 samples (31.0%), CDK6 in 18 samples (10.3%), pRB protein in 69 samples (39.7%), and cyclin D1 in 87 samples (50.0%). Multivariate analysis using the Cox proportional hazard regression model showed that invasion into cavernous sinus (hazard ratio [HR] of 4.02; P < 0.001), immunohistochemical normostaining for p16 (HR of 3.16; P < 0.001), immunohistochemical overstaining for pRB protein (HR of 2.45; P = 0.008), cyclin D1 (HR of 2.13; P = 0.029), MIB-1 antigen (HR of 2.74; P = 0.002), and p53 (HR of 2.21; P = 0.002), predicted the recurrence of FPA after surgical resection.

CONCLUSIONS

Our findings indicate that p16, pRB protein, and cyclin D1 are associated with recurrence FPA after surgical resection.

A new prognostic clinicopathological classification of pituitary adenomas: a multicentric case-control study of 410 patients with 8 years post-operative follow-up

Pituitary adenomas are currently classified by histological, immunocytochemical and numerous ultrastructural characteristics lacking unequivocal prognostic correlations. We investigated the prognostic value of a new clinicopathological classification with grades based on invasion and proliferation. This retrospective multicentric case-control study comprised 410 patients who had surgery for a pituitary tumour with long-term follow-up. Using pituitary magnetic resonance imaging for diagnosis of cavernous or sphenoid sinus invasion, immunocytochemistry, markers of the cell cycle (Ki-67, mitoses) and p53, tumours were classified according to size (micro, macro and giant), type (PRL, GH, FSH/LH, ACTH and TSH) and grade (grade 1a: non-invasive, 1b: non-invasive and proliferative, 2a: invasive, 2b: invasive and proliferative, and 3: metastatic). The association between patient status at 8-year follow-up and age, sex, and classification was evaluated by two multivariate analyses assessing disease- or recurrence/progression-free status. At 8 years after surgery, 195 patients were disease-free (controls) and 215 patients were not (cases). In 125 of the cases the tumours had recurred or progressed. Analyses of disease-free and recurrence/progression-free status revealed the significant prognostic value (p < 0.001; p < 0.05) of age, tumour type, and grade across all tumour types and for each tumour type. Invasive and proliferative tumours (grade 2b) had a poor prognosis with an increased probability of tumour persistence or progression of 25- or 12-fold, respectively, as compared to non-invasive tumours (grade 1a). This new, easy to use clinicopathological classification of pituitary endocrine tumours has demonstrated its prognostic worth by strongly predicting the probability of post-operative complete remission or tumour progression and so could help clinicians choose the best post-operative therapy.

Clinicopathological correlations in pituitary adenomas

Pituitary adenomas are common neuroendocrine neoplasms arising from adenohypophysial cells. Recent progress in our understanding of pituitary tumorigenesis as well as pathways involved in molecular cytodifferentiation of the adenohypophysis has impacted on the classification of pituitary adenomas. The detailed comprehensive classification of pituitary adenomas is now well recognized to reflect specific clinical features and genetic changes that predict targeted treatments, as well as prognostic information for patients with pituitary adenomas. Therefore, the clinical responsibility of pathologists is not only limited to the distinction of pituitary adenomas from other sellar lesions, but also to provide a comprehensive subtype classification using appropriate ancillary tools. In this article, we highlight an approach to clinical diagnosis and pitfalls in the classification of these common neoplasms.