Silent, but not unseen: multimicrocystic aspect on T2-weighted MRI in silent corticotroph adenomas

Analysis of MRI features and associated factors of the pituitary neuroendocrine tumor streaky sign

OBJECTIVES

Observation of pituitary neuroendocrine tumors with streaky sign on MRI, analysis of their features on imaging and further investigation of the relationship between the direction of the streak sign and the direction of optimal tumor expansion.

METHODS

The MR images of 237 patients with pituitary neuroendocrine tumors were retrospectively analyzed. The streaky-like high signal with a substantial length of more than 10 mm and obvious enhancement on T1WI was defined as the streaky sign. Finally, 66 patients were included in the study, comprising 33 patients with streaky sign pituitary neuroendocrine tumors and 33 randomly selected patients with non-streaky sign pituitary neuroendocrine tumors. The general condition of these 66 patients, the imaging features of the tumor, and the measurement and analysis of the direction of the streaky sign in relation to the direction of optimal tumor extension were observed and analyzed.

RESULTS

On MRI, 85 streaky signs were observed. The average deviation between the direction angle of all the streaky signs and the optimal extension direction angle of the tumor was approximately 11°. The longest streaky sign angle was positively correlated with the optimal extension angle of the tumor, with a correlation coefficient of 0.967.

CONCLUSION

The presence of a streaky sign of pituitary neuroendocrine tumors may indicate a dilated sinus or a small blood vessel. Its direction is highly consistent with the optimal extension direction of the tumor, which has a certain supporting effect on the long-distance growth of the tumor.

Is radiomics a useful addition to magnetic resonance imaging in the preoperative classification of PitNETs?

BACKGROUND

The WHO 2021 introduced the term pituitary neuroendocrine tumours (PitNETs) for pituitary adenomas and incorporated transcription factors for subtyping, prompting the need for fresh diagnostic methods. Current biomarkers struggle to distinguish between high- and low-risk non-functioning PitNETs. We explored if radiomics can enhance preoperative decision-making.

METHODS

Pre-treatment magnetic resonance (MR) images of patients who underwent surgery between 2015 and 2019 with available WHO 2021 classification were used. The tumours were manually segmented on the T1w, T1-contrast enhanced, and T2w images using 3D Slicer. One hundred Pyradiomic features were extracted from each MR sequence. Models were built to classify (1) somatotroph and gonadotroph PitNETs and (2) high- and low-risk subtypes of non-functioning PitNETs. Feature were selected independently from the MR sequences and multi-sequence (combining data from more than one MR sequence) using Boruta and Pearson correlation. Support vector machine (SVM), logistic regression (LR), random forest (RF), and multi-layer perceptron (MLP) were the classifiers used. Data imbalance was addressed using the Synthetic Minority Oversampling TEchnique (SMOTE). Performance of the models were evaluated using area under the receiver operating curve (AUC), accuracy, sensitivity, and specificity.

RESULTS

A total of 222 PitNET patients (train, n = 149; test, n = 73) were enrolled in this retrospective study. Multi-sequence-based LR model discriminated best between somatotroph and gonadotroph PitNETs, with a test AUC of 0.84, accuracy of 0.74, specificity of 0.81, and sensitivity of 0.70. Multi-sequence-based MLP model perfomed best for the high- and low-risk non-functioning PitNETs, achieving a test AUC of 0.76, accuracy of 0.67, specificity of 0.72, and sensitivity of 0.66.

CONCLUSIONS

Utilizing pre-treatment MRI and radiomics holds promise for distinguishing high-risk from low-risk non-functioning PitNETs based on the latest WHO classification. This could assist neurosurgeons in making critical decisions regarding surgery or alternative management strategies for PitNETs after further clinical validation.

Clinical Significance of T2-Weighted Sequence Intensity on Magnetic Resonance Imaging in Clinically Non-Functioning Pituitary Adenomas

BACKGROUND

Little is known about the relationship between signal intensity patterns on T2-weighted magnetic resonance imaging (MRI) in non-functioning pituitary adenomas (NFPAs).

OBJECTIVE

In this study, the clinical, hormonal, histological features, and therapeutic responses were evaluated according to the T2 signal intensity in NFPAs.

METHODS

This retrospective and multicenter study included a group of 166 NFPA patients (93 men, 56%, mean age 58.5 ±14.8 yr).

RESULTS

Approximately half of the tumors (n=84, 50.6%) were hyperintense, while 34.3% (n=57) and 15.1% (n=25) were iso- and hypointense, respectively. The median maximum tumor diameter of the isointense group [16 (13-25) mm] was significantly lower than that of the hyperintense [23 (16.6-29.7) mm] group (p=0.003). Similarly, the tumor volume of the isointense group [1,523 (618-5,226) mm3] was significantly lower than that of the hyperintense [4,012 (2,506-8,320) mm3] group (p=0.002). Chiasmatic compression occurred less frequently in tumors with isointense signal characteristics (38.6%) compared to tumors with hypointense (68%) and hyperintense (65.5%) signal characteristics (p=0.003). Invasive adenomas (p=0.001) and the degree of cavernous sinus invasion (p<0.001) were more frequent in the hyperintense adenoma group compared to the remaining groups. Plurihormonal tumors and silent lactotroph adenomas were more frequent in the isointense tumor group.

CONCLUSION

In conclusion, hyperintensity on T2-weighted MRI in NFPAs is associated with larger and more invasive tumors compared to isointense NFPAs.

Differentiation of silent corticotroph pituitary neuroendocrine tumors (PitNETs) from non-functioning PitNETs using kinetic analysis of dynamic MRI

PURPOSE

Silent corticotroph pituitary adenomas (SCAs)/pituitary neuroendocrine tumors (PitNETs) are common non-functioning pituitary adenomas (NFAs)/PitNETs with a clinically aggressive course. This study aimed to investigate the ability of time-intensity analysis of dynamic magnetic resonance imaging (MRI) for distinguishing adrenocorticotropic hormone (ACTH)-positive SCAs and ACTH-negative SCAs from other NFAs.

MATERIALS AND METHODS

We retrospectively evaluated the dynamic MRI findings of patients with NFAs. The initial slope of the kinetic curve (slopeini) obtained by dynamic MRI for each tumor was analyzed using a modified empirical mathematical model. The maximum slope of the kinetic curve (slopemax) was obtained by geometric calculation.

RESULTS

A total of 106 patients with NFAs (11 ACTH-positive SCAs, 5 ACTH-negative SCAs, and 90 other NFAs) were evaluated. The kinetic curves of ACTH-positive SCAs had significantly lesser slopeini and slopemax compared with ACTH-negative SCAs (P = 0.040 and P = 0.001, respectively) and other NFAs (P = 0.018 and P = 0.035, respectively). Conversely, the slopeini and slopemax were significantly greater in ACTH-negative SCAs than in NFAs other than ACTH-negative SCAs (P = 0.033 and P = 0.044, respectively). In receiver operating characteristic analysis of ACTH-positive SCAs and other NFAs, the area under the curve (AUC) values for slopeini and slopemax were 0.762 and 0748, respectively. In predicting ACTH-negative SCAs, the AUC values for slopeini and slopemax were 0.784 and 0.846, respectively.

CONCLUSIONS

Dynamic MRI can distinguish ACTH-positive SCAs and ACTH-negative SCAs from other NFAs.

Radiomics model and clinical scale for the preoperative diagnosis of silent corticotroph adenomas

OBJECTIVE

Silent corticotroph adenomas (SCAs) are a subtype of nonfunctioning pituitary adenomas that exhibit more aggressive behavior. However, rapid and accurate preoperative diagnostic methods are currently lacking.

DESIGN

The purpose of this study was to examine the differences between SCA and non-SCA features and to establish radiomics models and a clinical scale for rapid and accurate prediction.

METHODS

A total of 260 patients (72 SCAs vs. 188 NSCAs) with nonfunctioning adenomas from Peking Union Medical College Hospital were enrolled in the study as the internal dataset. Thirty-five patients (6 SCAs vs. 29 NSCAs) from Fuzhou General Hospital were enrolled as the external dataset. Radiomics models and an SCA scale to preoperatively diagnose SCAs were established based on MR images and clinical features.

RESULTS

There were more female patients (internal dataset: p < 0.001; external dataset: p = 0.028) and more multiple microcystic changes (internal dataset: p < 0.001; external dataset: p = 0.012) in the SCA group. MRI showed more invasiveness (higher Knosp grades, p ≤ 0.001). The radiomics model achieved AUCs of 0.931 and 0.937 in the internal and external datasets, respectively. The clinical scale achieved an AUC of 0.877 and a sensitivity of 0.952 in the internal dataset and an AUC of 0.899 and a sensitivity of 1.0 in the external dataset.

CONCLUSIONS

Based on clinical information and imaging characteristics, the constructed radiomics model achieved high preoperative diagnostic ability. The SCA scale achieved the purpose of rapidity and practicality while ensuring sensitivity, which is conducive to simplifying clinical work.

Imaging of pituitary tumors: an update with the 5th WHO Classifications-part 1. Pituitary neuroendocrine tumor (PitNET)/pituitary adenoma

The pituitary gland is the body's master gland of the endocrine glands. Although it is a small organ, many types of tumors can develop within it. The recently revised fifth edition of the World Health Organization (WHO) classifications (2021 World Health Organization Classification of Central Nervous System Tumors and 2022 World Health Organization Classification of Endocrine and Neuroendocrine Tumors) revealed significant changes to the classification of pituitary adenomas, the most common type of pituitary gland tumor. This change categorized pituitary adenomas as neuroendocrine tumors and proposed the name to be revised to pituitary neuroendocrine tumor (PitNET). The International Classification of Diseases for Oncology behavior code for this tumor was previously "0" for benign tumor. In contrast, the fifth edition WHO classification has changed this code to "3" for primary malignant tumors as same to neuroendocrine tumor in other organs. Because the WHO classification made an important and significant change in the fundamental concept of the disease, in this paper, we will discuss the imaging diagnosis (magnetic resonance imaging, computed tomography, and positron emission tomography) of PitNET/pituitary adenoma in detail, considering these revisions as per the latest version of the WHO classification.

Cystic versus non-cystic silent corticotrophic adenomas: clinical and histological analysis of 62 cases after microscopic transsphenoidal surgery-a retrospective, single-center study

Silent corticotrophic adenomas (SCAs) represent a rare group of non-functioning adenomas with a potentially aggressive clinical course. Cystic component is a very common finding among SCAs, but its clinical relevance has not yet been investigated. The aim of this study was to analyze clinical features of cystic and non-cystic SCAs, perioperative complications after microscopic transsphenoidal surgery, clinical outcome after first and repeat surgery along with risk factors for recurrence. We conducted a retrospective analysis of 62 silent corticotrophic adenomas treated at our university medical center via microscopic transsphenoidal surgery between January 2008 and July 2019. Parameters investigated included histology, invasiveness, intratumoral haemorrhage or cystic component on MRI, perioperative alteration of visual field, tumor size, pre- and postoperative ACTH, FSH, GH, LH, TSH, prolactin, cortisol, free T4, free T3, IGF-1, estrogen and testosterone levels, perioperative complications, neoadjuvant and adjuvant therapy along with clinical outcomes. A total of 62 patients were analyzed. The mean follow up was 28.3 months. Tumors with a cystic component occur statistically significant more often among male than non-cystic (80.6% vs. 44.4%, p = 0.02) and display lower rates of cavernous sinus invasion and sphenoid sinus invasion were significantly lower for cystic lesions comparing to non-cystic tumors (42.3% vs. 69.4%, p = 0.04 and 3.8% vs. 47.2%, p < 0.001). GTR after MTS was not statistically significant higher by cystic SCAs (80% vs. 57.1%, p = 0.09). Cystic lesions were also associated with higher risk of hyperprolactinemia (19.4% vs. 2.8%, p = 0.02) and only densely granulated cystic SCAs presented with preoperative intratumoral hemorrhage (19.2% vs. 0%, p = 0.01). Mean duration of first surgery was significantly shorter for cystic SCAs (71.6(± 18.7) vs. 94.8(± 31.1) minutes, p = 0.01). Preoperative pituitary insufficiency (25% vs. 16.7%, p = 0.49), intraoperative CSF space opening (21.1% vs. 37.5%, p = 0.32), along with postoperative new pituitary insufficiency (15% vs. 10%, p = 0.67) or diabetes insipidus/SIADH (10% vs. 13.3%, p > 0.99) with histological markers such as Ki67 (21.1% vs. 13.8%, p = 0.70) and p53 expression (6.3% vs. 0%, p = 0.39) as well as mitotic rate (5.3% vs. 10.3%, p > 0.99) were comparable between both groups. The presence of cystic component did not affect the tumor recurrence (10% vs. 16%, p = 0.68). Mean duration of surgery was first surgeries was not statistically shorter than repeat surgeries (85.4 ± 29.1 vs. 93.8 ± 28 min, p = 0.15). Patients undergoing first surgery had a higher probability of gross total resection (74.4% vs. 30%, p = 0.01) and lower probability of intraoperative CSF space opening (26% vs. 58.3%, p = 0.04) as well as a lower rate of preoperative anterior pituitary insufficiency (20% vs. 58.3%, p = 0.01). The incidence of new postoperative anterior pituitary insufficiency (10% vs. 0%, p = 0.57) and transient diabetes insipidus/SIADH (12% vs. 8.3%, p > 0.99) between those groups were comparable. No statistical difference was observed between patients with remission and with recurrent tumor regarding cortisol and ACTH levels, incidence of different histological subgroups, invasively growing tumors and lesions with cystic components as well as the percentage of cases with increased Ki67 proliferation index, p53 expression and mitotic indices. Our study presents one of the largest available cohorts of SCAs after microscopic transsphenoidal surgery and first clinical analysis of cystic versus non-cystic SCAs so far. We also performed the first comparison of index and repeat surgeries for this tumor entity. Cystic tumors presented with characteristic clinical aspects like male predominance, higher risk of hyperprolactinemia as well as lower rates of cavernous sinus and sphenoid sinus invasion comparing to non-cystic lesions. Mean duration of first surgery was significantly shorter for cystic SCAs. Moreover preoperative intratumoral hemorrhage had 100% specificity and 60% sensitivity for densely granulated cystic SCAs. All these clinical hallmarks may suggest a novel subgroup of SCAs with distinct clinical and biological features, however further clinical and molecular investigations are required. Second surgeries are associated with a higher incidence of preoperative pituitary insufficiency, and a higher risk of subtotal resection, and a higher probability of CSF space opening intraoperatively compared to first surgeries. On the other hand, the risk of new postoperative pituitary insufficiency was higher after first surgeries. In our cohort of patients, no prognostic factor for recurrence among histological diagnosis, Ki67-proliferation index, p53 expression, number of mitoses, invasive growth or cystic lesions for SCAs could be detected.

Application of “mosiac sign” on T2-WI in predicting the consistency of pituitary neuroendocrine tumors

Purpose

Tumor consistency is important for pituitary neuroendocrine tumors (PitNETs) resection to improve surgical outcomes. In this study, we evaluated the T2-WI of PitNETs and defined a specific T2-WI signaling manifestation, the “Mosaic sign,” to predict tumor consistency and resection of PitNETs.

Design

A retrospective review of MRI and tumor histology of 137 consecutive patients who underwent endoscopic endonasal resection for PitNETs was performed.

Methods

The “Mosaic sign” was defined by the ratio of the tumor itself T2-WI signals, and characterized by multiple intratumor hyperintense dots. The degree of tumor resection was an assessment by postoperative MRI examination. The presence of the “Mosaic sign” was compared with patients' basic information, tumor consistency, tumor pathological staining, and surgical result. To determine whether the presence or absence of “Mosaic sign” could predict tumor consistency and guide surgical resection of tumors.

Results

Statistical analysis showed that the consistency of the tumor and the degree of resection were correlated with the “Mosaic sign”. In the 137 cases of T2-WI, 43 had “Mosaic sign”, 39 cases had soft tumor consistency, and 4 were classified as fibrous, of which 42 were completely resected and 1 was subtotal resected. Of the 94 patients without “Mosaic sign”, the consistency of tumor of 54 cases were classified as soft, the remaining 40 cases were fibrous, 80 cases were completely resected, and 14 cases were subtotal resected. Postoperative cerebrospinal fluid leakage occurred in 1 patient. The number of corticotroph adenomas in the group of “Mosaic sign” was higher, with the statistical difference between the two groups (P = 0.0343).

Conclusions

The presence of the “Mosaic sign” in T2-WI may provide preoperative information for pituitary adenomas consistency and effectively guide surgical approaches.

Contrast-enhanced 3D-T2-weighted SPACE sequence for MRI detection and localization of adrenocorticotropin (ACTH)-secreting pituitary microadenomas

OBJECTIVE

Cushing disease is a potentially fatal endocrine disorder caused by adrenocorticotropin (ACTH)-secreting microadenomas in the pituitary gland. Accurate detection and localization of the adenomas is the key to clinical treatment. This study analysed the value of contrast-enhanced Sampling Perfection with Application-optimized Contrasts using different flip angle Evolutions (SPACE) sequence in magnetic resonance imaging (MRI) assessment of ACTH-secreting pituitary microadenomas.

DESIGN AND PATIENTS

We carried out a retrospective study in which 45 patients with ACTH-secreting pituitary microadenomas were enrolled. Dynamic contrast-enhanced (DCE) coronal T1-SE sequence was performed. A contrast-enhanced coronal SPACE sequence was added immediately after DCE MRI finished. Two independent observers assessed the tumour existence and location, then the results were compared with surgical findings.

RESULTS

Twenty-four lesions (53.3%) were detected by the DCE T1-SE sequence alone, while 35 lesions (80.0%) were detected with the addition of contrast-enhanced SPACE sequence. The sensitivity (58.5% vs. 85.3%; p < .05) and best diagnostic accuracy (62.0% vs. 84.4%; p < .05) were significantly better for addition with SPACE sequence than DCE-SE images alone in detection of ACTH-secreting pituitary microadenomas. For lesions <5 mm, the detected numbers were 4 (16.6%) versus 10 (27.8%) by DCE T1-SE sequence and combined DCE T1-SE with SPACE sequence.

CONCLUSIONS

A combination of contrast-enhanced SPACE with DCE T1-SE sequence could improve the detection of ACTH-secreting pituitary microadenomas. Contrast-enhanced SPACE sequence could be a supplementary sequence for imaging of ACTH-secreting pituitary adenomas when T1-SE sequence provides negative or equivocal findings.

Sparsely Granulated Corticotroph Pituitary Macroadenoma Presenting with Pituitary Apoplexy Resulting in Remission of Hypercortisolism

Objective

Case Report

Discussion

Conclusion

An Update on Silent Corticotroph Adenomas: Diagnosis, Mechanisms, Clinical Features, and Management

Simple Summary

The 2017 World Health Organization classification of endocrine tumors defines pituitary adenomas based on their cell lineages. T-PIT can serve as a complimentary tool for further identification of silent corticotroph adenomas (SCAs). Unlike functioning corticotroph adenomas in patients with Cushing’s disease, SCAs present no clinical and biochemical features of Cushing’s syndrome. SCAs have been shown to exhibit a more aggressive course characterized by a higher probability of recurrence and resistance to conventional treatment due to their intrinsic histological features. The aim of our review is to offer an update on the diagnosis, mechanisms, clinical features and management of SCAs. Studies of the molecular mechanisms of SCA pathogenesis will provide new directions for the diagnosis and management of SCAs.

Abstract

With the introduction of 2017 World Health Organization (WHO) classification of endocrine tumors, T-PIT can serve as a complementary tool for identification of silent corticotroph adenomas (SCAs) in some cases if the tumor is not classifiable by pituitary hormone expression in pathological tissue samples. An increase of the proportion of SCAs among the non-functioning pituitary adenomas (NFPAs) has been witnessed under the new rule with the detection of T-PIT-positive ACTH-negative SCAs. Studies of molecular mechanisms related to SCA pathogenesis will provide new directions for the diagnosis and management of SCAs. A precise pathological diagnosis can help clinicians better identify SCAs. Understanding clinical features in the context of the pathophysiology of SCAs is critical for optimal management. It could provide information on appropriate follow-up time and aid in early recognition and treatment of potentially aggressive forms. Management approaches include surgical, radiation, and/or medical therapies.

A clinicoradiological analysis of silent corticotroph adenomas after the introduction of pituitary-specific transcription factors

BACKGROUND

Silent corticotroph adenomas (SCAs) are a rare subtype of non-functional pituitary adenoma. While it has been suggested that they are more aggressive and recur more frequently following excision, there is limited literature on the optimum treatment strategy for these tumors, especially regarding the role of radiation therapy in incompletely resected tumors.

METHOD

We assimilated data from 62 SCAs and 238 other non-functional adenomas (ONAs), defined according to the WHO 2017 criteria that incorporates transcription factor analysis. We compared their clinicoradiological characteristics, such as hormonal levels, tumor configuration, size, and invasiveness. For 52 SCAs and 205 ONAs with serial follow-up imaging, we studied outcomes for progression after subtotal resection with or without radiation therapy or recurrence after gross total resection. Kaplan Meier analysis for recurrence or progression was used to determine the need for a differential treatment strategy for SCAs compared with other non-functional adenomas specifically concerning the role of radiotherapy.

RESULTS

Patients with SCAs present at a younger age than ONAs (43.9 years vs. 48.2 years, p = 0.014), with larger (14.9 cc vs. 9.7 cc, p = 0.006) and more invasive adenomas (61.2% vs. 45.8%, p = 0.021). Overall, SCAs are more likely to recur or progress (48.7 vs. 15.7%, p < 0.001) following excision than ONAs, with significantly poorer event-free survival (Log rank test p < 0.001). Early adjuvant radiotherapy provides favorable outcomes among SCAs with postoperative residual tumor, on par with ONAs. Multivariate analysis identified male gender (HR: 2.217; p = 0.017), MIB index ≥ 3% (HR: 2.116; p = 0.012), and SCA tumor pathology (HR: 3.787; p < 0.001) as factors predicting recurrence.

CONCLUSIONS

Based on the results of this retrospective, single-center review of 300 non-functional adenomas, we conclude that silent corticotroph adenomas are an aggressive subtype of non-functional pituitary adenomas that are larger, more likely to be invasive, and tend to recur more frequently after a subtotal excision compared with other non-functional adenomas. A gross total resection must be attempted whenever possible and earlier adjuvant radiation is recommended when re-surgery for residual tumor is difficult.

Current opinion on the diagnosis and management of non-functioning pituitary adenomas

INTRODUCTION

Non-functioning pituitary adenomas (NFPAs) are clinically silent tumors and the second most common pituitary adenoma. Surgery is the mainstay of treatment as there is, as yet, no effective medical treatment.

AREAS COVERED

We present current knowledge on the clinical diagnosis, histopathological classification, molecular data, and management strategies in NFPA.

EXPERT OPINION

NFPA is a heterogeneous group of tumors, in respect to their origin and clinical course. In recent years, research on pathology and molecular biology have advanced our knowledge of NFPA pathogenesis. NFPA exhibit, in the majority of cases, an indolent behavior, with satisfactory response to treatment. In aggressive cases, multimodal management is needed; however, even this approach may be insufficient, so the development of new treatments is warranted for better management. In this setting, the understanding of the mechanisms involved in the genesis and progression of NFPA is crucial for the identification and development of directed treatments with higher chances of response.

Aggressive Cushing's Disease: Molecular Pathology and Its Therapeutic Approach

Cushing's disease is a syndromic pathological condition caused by adrenocorticotropic hormone (ACTH)-secreting pituitary adenomas (ACTHomas) mediated by hypercortisolemia. It may have a severe clinical course, including infection, psychiatric disorders, hypercoagulability, and metabolic abnormalities, despite the generally small, nonaggressive nature of the tumors. Up to 20% of ACTHomas show aggressive behavior, which is related to poor surgical outcomes, postsurgical recurrence, serious clinical course, and high mortality. Although several gene variants have been identified in both germline and somatic changes in Cushing's disease, the pathophysiology of aggressive ACTHomas is poorly understood. In this review, we focused on the aggressiveness of ACTHomas, its pathology, the current status of medical therapy, and future prospects. Crooke's cell adenoma (CCA), Nelson syndrome, and corticotroph pituitary carcinoma are representative refractory pituitary tumors that secrete superphysiological ACTH. Although clinically asymptomatic, silent corticotroph adenoma is an aggressive ACTH-producing pituitary adenoma. In this review, we summarize the current understanding of the pathophysiology of aggressive ACTHomas, including these tumors, from a molecular point of view based on genetic, pathological, and experimental evidence. The treatment of aggressive ACTHomas is clinically challenging and usually resistant to standard treatment, including surgery, radiotherapy, and established medical therapy (e.g., pasireotide and cabergoline). Temozolomide is the most prescribed pharmaceutical treatment for these tumors. Reports have shown that several treatments for patients with refractory ACTHomas include chemotherapy, such as cyclohexyl-chloroethyl-nitrosourea combined with 5-fluorouracil, or targeted therapies against several molecules including vascular endothelial growth factor receptor, cytotoxic T lymphocyte antigen 4, programmed cell death protein 1 (PD-1), and ligand for PD-1. Genetic and experimental evidence indicates that some possible therapeutic candidates are expected, such as epidermal growth factor receptor tyrosine kinase inhibitor, cyclin-dependent kinase inhibitor, and BRAF inhibitor. The development of novel treatment options for aggressive ACTHomas is an emerging task.

Multidisciplinary protocol of preoperative and surgical management of patients with pituitary tumors candidates to pituitary surgery

The optimal planning of preoperative diagnosis, management and treatment of pituitary tumors (PT) candidates to pituitary surgery (PS) requires a multidisciplinary approach involving a team of endocrinologists, neurosurgeons, ENT, neuro-ophthalmologists and neuroradiologists with experience in pituitary diseases. Such teams improve surgical results, minimize complications and facilitate their correct treatment if occurring, and optimize the hormonal, ophthalmological and radiological preoperative and follow-up evaluation. We have developed a clinical practice protocol for patients with PT who are candidates to PS based on the most recent national and international guidelines and the relevant literature regarding PT published in the last years. The protocol has been elaborated by a multidisciplinary team of a Spanish Pituitary Tumor Center of Excellence (PTCE) that includes at least one neurosurgeon, ENT, neuroradiologist, neuro-ophthalmologist, endocrine pathologist and endocrinologist specialized in pituitary diseases. We elaborated this guideline with the aim of sharing our experience with other centers involved in the perioperative and surgical management of PT thereby facilitating the management of patients undergoing PS.

Cystic appearance on magnetic resonance imaging in bihormonal growth hormone and prolactin tumors in acromegaly

PURPOSE

To investigate demographic, imaging and laboratory characteristics, and treatment outcomes of acromegaly patients who have bihormonal (BA) growth hormone (GH) and prolactin (PRL) immunoreactive adenomas compared to patients who have densely granulated GH adenomas (DGA) and sparsely granulated GH adenomas (SGA).

METHODS

Retrospective review of single-center surgically treated acromegaly patients; pathology was analyzed by a single neuropathologist using 2017 WHO criteria. Preoperative magnetic resonance imaging was assessed to evaluate tumor size, cystic component, invasion and T2 signal intensity.

RESULTS

Seventy-seven patients; 19 BA (9 mammosomatotroph and 10 mixed GH and PRL adenomas) were compared with 30 DGA, and 28 SGA. Patients with BA were older than SGA (49.6 vs 38.5 years, p = 0.035), had a higher IGF-1 index (3.3 vs 2.3, p = 0.040) and tumors were less frequently invasive (15.8% vs 57.1%, p = 0.005). BA more frequently had a cystic component on MRI than both SGA and DGA (52.6% vs 14.3%, and 22%, p = 0.005 and 0.033, respectively). When all histological types were combined, biochemical remission postoperatively was more common in non-cystic than cystic tumors (50% vs 22.5%, p = 0.042). Somatostatin receptor ligand response rate was 66.7%, 90.9% and 37.5% in BA, DGA and SGA patients, respectively (p = 0.053).

CONCLUSION

Imaging characteristics are an increasingly important adenoma behavior determinant. An adenoma cystic component may suggest that a GH adenoma is a BA. Cystic tumors exhibited lower rates of surgical remission in this series; therefore, optimized individual patient treatment is needed, as patients could be candidates for primary medical treatment.

Advances in the Imaging of Pituitary Tumors

In most patients with pituitary adenomas magnetic resonance imaging (MRI) is essential to guide effective decision-making. T1- and T2-weighted sequences allow the majority of adenomas to be readily identified. Supplementary MR sequences (e.g. FLAIR; MR angiography) may also help inform surgery. However, in some patients MRI findings are 'negative' or equivocal (e.g. with failure to reliably identify a microadenoma or to distinguish postoperative change from residual/recurrent disease). Molecular imaging [e.g. ¹¹C-methionine PET/CT coregistered with volumetric MRI (Met-PET/MR^CR)] may allow accurate localisation of the site of de novo or persistent disease to guide definitive treatment (e.g. surgery or radiosurgery).

Neuroimaging of aggressive pituitary tumors

Aggresssive pituitary tumors are defined as radiologically invasive, exhibiting a rapid growth and a poor response to the medical and surgical treatment options. The role of magnetic resonance imaging (MRI) is fundamental to assess tumor aggressiveness before surgical exploration. Distinction between cavernous sinus invasion and cavernous sinus compression is often challenging and cannot be solved always by using the Knosp criteria. Ideally, T2W images demonstrating the ruptured internal dural wall of cavernous sinus is the ultimate proof of cavernous sinus invasion. Subtle tumor volume increase in a short time can be shown when sequential MR images are rigorously replicable. A microcystic pattern observed on T2W images frequently reflects a potentially aggressive tumor as observed in silent corticotroph pituitary adenomas.

Accuracy of microcystic aspect on T2-weighted MRI for the diagnosis of silent corticotroph adenomas

INTRODUCTION

A single study suggested that silent corticotropinomas (SCAs) have a different imaging phenotype, with microcystic aspect on T2-weighted sequence of magnetic resonance imaging (T2-MRI). This study only analysed manifest and silent corticotropinomas and nonfunctioning gonadotroph adenomas. Therefore, the prevalence of microcystic patterns of other tumours is not known.

AIM

To analyse frequency of microcystic patterns on T2-MRI in all subtypes of pituitary adenomas and determine accuracy of this radiological finding for diagnosing SCA.

METHODS

Consecutive pituitary adenoma patients who underwent surgery between 2013 and 2016 at a single centre were included. T2-MRIs were evaluated by a radiologist and an endocrinologist blinded to histological diagnosis.

RESULTS

A total of 143 patients (52% female) with median age of 49 years (14-80) were included. Clinically, there were 90 nonfunctioning pituitary adenomas (NFPAs), 32 somatotropinomas, 13 corticotropinomas, five prolactinomas and three TSH-secreting adenomas. Of the patients with NFPA, 12 (13%) were SCAs, 73 (79%) were gonadotropinomas and five (6%) were positive for prolactin (three) or TSH (two). A microcystic pattern was observed in 16 tumours (11%): one somatotropinoma, one corticotropinoma, seven SCAs and seven gonadotropinomas, and in no prolactinomas or TSH-secreting adenomas. It was more common in SCAs than in other tumours (58.3% vs 6.9%, respectively, P < .001) and had a sensitivity of 58%, a specificity of 93% and an accuracy of 90% to define an SCA.

CONCLUSION

Microcystic aspect on T2-MRI is able to define SCA with a good accuracy and can be a useful tool, considering the more aggressive behaviour of these tumours.

Clinical, Laboratory, and Treatment Profiles of Silent Corticotroph Adenomas That Have Transformed to the Functional Type: A Case Series With a Literature Review

Purpose: Silent corticotroph adenoma (SCA) is clinically non-functional pituitary adenoma with expression of corticotropin or Tpit. To further understand the characteristics of this rare type of SCA transforming to a functional SCA, we retrospectively reviewed SCAs that converted to typical Cushing's syndrome at a tertiary medical center and the relevant literature. Methods: Patients were identified based on the diagnosis of pituitary adenoma without symptoms of hypercortisolism at the initial visit with positive Immunohistochemical (IHC) staining for corticotropin or Tpit after surgery and subsequent transformation to functional SCAs during the follow-up period from March 1990 to January 2020 at Peking Union Medical College Hospital and in the literature. The characteristics of the clinical manifestations, biochemical results, imaging findings, pathology findings and outcome were analyzed. Results: Altogether, 16 patients were included in the study with an average age of 42.0 ± 12.48 (18-65) years at the first visit. Females were slightly predominant (F:M = 1.3:1). The median time of conversion from the nonfunctional to the functional type was 30 (13.0, 68.3) months. Once a functional SCA developed, the adrenocorticotropic hormone (ACTH) level and 24-h urine free cortisol were increased 3.8- (2.6, 12.9) and 5.3- (2.6, 19.3) fold, respectively, above the normal range. Approximately 50% of the patients had macrocystic changes on pituitary MRI. All 16 patients experienced 1-5 surgeries with a median of 2.5 (2.0, 4.0) surgeries. The proportion of patients with Ki-67 ≥ 3% increased from 22.2% (2/9) at the beginning to 50% (7/14) at the time of functional SCA diagnosis. Thirteen patients received radiotherapy, and 4 patients (30.8%) achieved remission. Four patients with refractory functional SCAs received temozolomide treatment with the normalization of cortisol in 4 cases and reduced tumor volume in 3 cases. Conclusion: In this study, all cases that transformed to functional SCAs were macroadenomas. Hypercortisolism was more severe in functional SCA patients. The tumors tended to have frequent recurrence and were highly invasive. Temozolomide could be a promising treatment for refractory functional SCA cases. Long-term follow-up is needed for nonfunctional SCAs since some cases have the potential to transform to clinical Cushing's syndrome.

Clinical and Pathological Aspects of Silent Pituitary Adenomas

CONTEXT

Silent pituitary adenomas are anterior pituitary tumors with hormone synthesis but without signs or symptoms of hormone hypersecretion. They have been increasingly recognized and represent challenging diagnostic issues.

EVIDENCE ACQUISITION

A comprehensive literature search was performed using MEDLINE and EMBASE databases from January 2000 to March 2018 with the following key words: (i) pituitary adenoma/tumor and nonfunctioning; or (ii) pituitary adenoma/tumor and silent. All titles and abstracts of the retrieved articles were reviewed, and recent advances in the field of silent pituitary adenomas were summarized.

EVIDENCE SYNTHESIS

The clinical and biochemical picture of pituitary adenomas reflects a continuum between functional and silent adenomas. Although some adenomas are truly silent, others will show some evidence of biochemical hypersecretion or could have subtle clinical signs and, therefore, can be referred to as clinically silent or "whispering" adenomas. Silent tumors seem to be more aggressive than their secreting counterparts, with a greater recurrence rate. Transcription factors for pituitary cell lineages have been introduced into the 2017 World Health Organization guidelines: steroidogenic factor 1 staining for gonadotroph lineage; PIT1 (pituitary-specific positive transcription factor 1) for growth hormone, prolactin, and TSH lineage, and TPIT for the corticotroph lineage. Prospective studies applying these criteria will establish the value of the new classification.

CONCLUSIONS

A concise review of the clinical and pathological aspects of silent pituitary adenomas was conducted in view of the new World Health Organization classification of pituitary adenomas. New classifications, novel prognostics markers, and emerging imaging and therapeutic approaches need to be evaluated to better serve this unique group of patients.

Modern imaging of pituitary adenomas

Decision-making in pituitary disease is critically dependent on high quality imaging of the sella and parasellar region. Magnetic resonance imaging (MRI) is the investigation of choice and, for the majority of patients, combined T1 and T2 weighted sequences provide the information required to allow surgery, radiotherapy (RT) and/or medical therapy to be planned and long-term outcomes to be monitored. However, in some cases standard clinical MR sequences are indeterminate and additional information is needed to help inform the choice of therapy for a pituitary adenoma (PA). This article reviews current recommendations for imaging of PA, examines the potential added value that alternative MR sequences and/or CT can offer, and considers how the use of functional/molecular imaging might allow definitive treatment to be recommended for a subset of patients who would otherwise be deemed unsuitable for (further) surgery and/or RT.

GLUT3 expression in cystic change induced by hypoxia in pituitary adenomas

Tumor cells require large amounts of energy to sustain growth. Through the mediated transport of glucose transporters, the uptake and utilization of glucose by tumor cells are significantly enhanced in the hypoxic microenvironment. Pituitary adenomas are benign tumors with high-energy metabolisms. We aimed to investigate the role of expression of glucose transporter 3 (GLUT3) and glucose transporter 1 (GLUT1) in pituitary adenomas, including effects on size, cystic change and hormone type. Pituitary adenomas from 203 patients were collected from January 2013 to April 2017, and immunohistochemical analysis was used to detect the expression of GLUT3 and GLUT1 in tumor specimens. GLUT3-positive expression in the cystic change group was higher than that in the non-cystic change group (P = 0.018). Proportions of GLUT3-positive staining of microadenomas, macroadenomas, and giant adenomas were 22.7 (5/22), 50.4 (66/131) and 54.0% (27/50), respectively (P = 0.022). In cases of prolactin adenoma, GLUT3-positive staining was predominant in cell membranes (P = 0.000006), while in cases of follicle-stimulating hormone or luteotropic hormone adenoma, we found mainly paranuclear dot-like GLUT3 staining (P = 0.025). In other hormonal adenomas, GLUT3 was only partially expressed, and the intensity of cell membrane or paranuclear punctate staining was weak. In contrast to GLUT3, GLUT1 expression was not associated with pituitary adenomas. Thus, our results indicate that the expression of GLUT3 in pituitary adenomas is closely related to cystic change and hormonal type. This study is the first to report a unique paranuclear dot-like GLUT3 staining pattern in pituitary adenomas.

Clinicopathological significance of baseline T2-weighted signal intensity in functional pituitary adenomas

PURPOSE

To assess baseline T2-weighted signal intensity (T2-WSI) of functional pituitary adenomas (FPA), and to investigate the relationship of baseline T2-WSI with clinical features, histopathological granulation patterns, and response to treatment in patients with acromegaly, prolactinoma and Cushing's disease (CD).

METHODS

Somatotroph adenomas (n = 87), prolactinomas (n = 78) and corticotroph adenomas (n = 29) were included in the study. Baseline T2-WSI findings (grouped as hypo-, iso- and hyperintense) were compared with hormone levels, tumor diameter, granulation patterns and response to treatment.

RESULTS

Somatotroph adenomas were mostly hypointense (53%), prolactinomas were dominantly hyperintense (55%), and corticotroph adenomas were generally hyperintense (45%). Hyperintense somatotroph adenomas were larger in size with sparsely granulated pattern and tumor shrinkage rate was lower after somatostatin analogues (SSA) (p = 0.007, p = 0.035, p = 0.029, respectively). T2 hypointensity was related with higher baseline IGF-1% ULN (upper limit of normal) levels and a better response to SSA treatment (p = 0.02, p = 0.045, respectively). In female prolactinomas, hyperintensity was correlated with a smaller adenoma diameter (p = 0.001). Hypointense female prolactinomas were related to younger age at diagnosis, higher baseline PRL levels and dopamine agonist (DA) resistance (p = 0.009, p = 0.022, p < 0.001, respectively). Hyperintense corticotroph adenomas were related to larger adenoma size and sparsely granulated pattern (p = 0.04, p = 0.017, respectively). There was no significant difference in the recurrence with T2WSI in CD.

CONCLUSION

Baseline hypointense somatotroph adenomas show a better response to SSA, whereas hypointensity was related to DA resistance in female prolactinomas.

Predictors of silent corticotroph adenoma recurrence; a large retrospective single center study and systematic literature review

PURPOSE

Silent corticotroph adenomas (SCAs) are clinically silent and non-secreting, but exhibit positive adrenocorticotropic hormone (ACTH) immunostaining. We characterized a single center cohort of SCA patients, compared the SCAs to silent gonadotroph adenomas (SGAs), identified predictors of recurrence, and reviewed and compared the cohort to previously published SCAs cases.

METHODS

Retrospective review of SCA and SGA surgically resected patients over 10 years and 6 years, respectively. Definitions; SCA-no clinical or biochemical evidence of Cushing's syndrome and ACTH positive immunostaining, and SGA-steroidogenic factor (SF-1) positive immunostaining. A systematic literature search was undertaken using Pubmed and Scopus.

RESULTS

Review revealed 814 pituitary surgeries, 39 (4.8%) were SCAs. Mean follow-up was 6.4 years (range 0.5-23.8 years). Pre-operative magnetic resonance imaging demonstrated sphenoid and/or cavernous sinus invasion in 44%, 33% were > 50% cystic, and 28% had high ACTH levels pre-operatively. Compared to SGAs (n = 70), SCAs were of similar size and invasiveness (2.5 vs. 2.9 cm, p = 0.2; 44 vs. 41%, p = 0.8, respectively), but recurrence rate was higher (36 vs. 10%, p = 0.001) and more patients received radiation therapy (18 vs. 3%, p = 0.006). Less cystic tumors (0 vs. 50%, p < 0.001) and higher pre-operative ACTH levels (54 vs. 28 pg/ml, p = 0.04) were predictors of recurrence for SCAs.

CONCLUSION

This review is unique; a strict definition of SCA was used, and single center SCAs were compared with SGAs and with SCAs literature reviewed cases. We show that SCAs are aggressive and identify predictors of recurrence. Accurate initial diagnosis, close imaging and biochemical follow up are warranted.

Prevalence of clinically silent corticotroph macroadenomas

OBJECTIVE

The prevalence of clinically silent corticotroph macroadenomas is unknown. Our aim was to determine the prevalence of clinically silent corticotroph macroadenomas among all pituitary macroadenomas.

DESIGN

Patients scheduled to have transsphenoidal surgery for any sellar mass were prospectively evaluated clinically and biochemically.

PATIENTS

Adults who were scheduled for transsphenoidal surgery for a sellar mass at a single academic medical centre.

MEASUREMENTS

Patients were assessed clinically prior to surgery and graded as having typical, mild or no Cushingoid features. They were assessed biochemically by plasma ACTH and 24-h urine free cortisol (UFC). Excised tissue was examined histologically, and pituitary macroadenomas, examined by immunohistochemistry. Patients with corticotroph macroadenomas were classified as clinically silent if they exhibited no Cushingoid features but had elevated plasma ACTH and/or 24-h UFC. They were classified as totally silent if they exhibited neither Cushingoid features nor elevated plasma ACTH or 24-h UFC.

RESULTS

Of 124 patients who had pathologically confirmed pituitary macroadenomas, 20 (16%) had corticotroph macroadenomas. Eight (40%) of these were clinically silent, in that they had no Cushingoid features but could be identified biochemically by elevated plasma ACTH (seven) and/or 24-h UFC (three). Five (25%) were totally silent.

CONCLUSIONS

A substantial minority (16%) of pituitary macroadenomas treated surgically are corticotroph adenomas. Of these, 40% are clinically silent but can be recognized by elevated plasma ACTH and/or 24-h UFC. Recognizing these adenomas may influence the surgical approach and provide a marker by which to follow the response to treatment.

Effect of Gonadotropin and Adrenocorticotropic Hormone Secretion on Invasiveness of Clinically Nonfunctioning Pituitary Adenomas: A Cell Culture Study

OBJECTIVE

The aim of this study was to clarify the correlation between clinical features (especially cyst formation and cavernous sinus invasion) and minor secretion of anterior pituitary hormones, especially adrenocorticotropic hormone (ACTH) and gonadotropin, by clinically nonfunctioning pituitary adenomas (CNFPAs) in cell culture.

METHODS

We examined anterior pituitary hormones secreted by samples from 63 cases of CNFPAs grown in cell culture. Magnetic resonance imaging, including determination of the Knosp grade, cystic changes, and intraoperative cavernous sinus invasion, was performed.

RESULTS

Detection of minor hormone secretion using cell culture showed that 61.9% (39/63) of CNFPAs secreted luteinizing hormone, follicle-stimulating hormone, and thyroid-stimulating hormone, 44.4% (28/63) secreted ACTH, 57.1% (36/63) secreted prolactin, and 28.6% (18/63) secreted growth hormone; only 1 case of the null-cell adenoma was observed (1.6%). Cystic changes, Knosp grade 4 status, and cavernous sinus invasion were predominantly observed in cases of ACTH-secreting adenomas. Gonadotropin-secreting adenomas showed opposite characteristics to ACTH-secreting adenomas.

CONCLUSIONS

Minor secretion of ACTH and gonadotropin may be related to clinical features, especially cystic changes and invasiveness of CNFPAs, suggesting that our cell culture method could be helpful for elucidating the mechanisms of pituitary cyst formation and the invasiveness of CNFPAs.

Silent corticotroph adenomas

PURPOSE

Silent corticotroph adenomas (SCAs) comprise 20% of all corticotroph adenomas and 3-19% of nonfunctioning adenomas (NFAs). As they do not manifest clinical or biochemical hypercortisolism, they are diagnosed after pathologic examination of resected tumor tissue demonstrates positive ACTH expression. While preoperative features are similar to those of NFAs, SCAs may have more cavernous sinus invasion. Further, patients with SCAs tend to have more frequent and earlier recurrences than those with NFAs, often necessitating multiple surgeries and other modalities of treatment. This article reviews the incidence, pathogenesis, and clinical behavior of SCAs.

METHODS

A systematic literature review was performed using PubMed for information regarding SCAs.

RESULTS

Up to date findings regarding epidemiology, pathogenesis, pathology, clinical presentation, postoperative course, and management of patients with SCAs are presented.

CONCLUSION

This review highlights the necessity of rigorous monitoring for recurrences and hypopituitarism in patients with SCAs.

Silent pituitary adenomas

Pituitary adenomas are frequently silent. Among silent adenomas, some are clinically silent but can be detected on the basis of the excessive secretion of hormonal products, whereas others are totally silent and cannot be detected by hormonal measurements. Treatment of a silent pituitary adenoma depends on its size and extent. Silent adenomas that are associated with neurologic compromise should be treated by surgery. Postoperative radiation therapy may be used to prevent or treat recurrences. Only occasional silent pituitary adenomas respond to treatment with dopamine agonists or somatostatin analogs.