Clinically silent corticotroph tumors of the pituitary gland

An update on, and genetics of refractory adenomas of childhood

Pituitary adenomas in childhood tend to be more frequently due to germline genetic changes and are often diagnosed at late stages due to delayed recognition by pediatricians and other caretakers who are not familiar with this rare disease in childhood. As a result, often, pediatric pituitary adenomas are aggressive or remain refractory to treatment. In this review, we discuss germline genetic defects that account for the most common pediatric pituitary adenomas that are refractory to treatment. We also discuss some somatic genetic events, such as chromosomal copy number changes that characterize some of the most aggressive pituitary adenomas in childhood that end up being refractory to treatment.

An Overview of Pituitary Incidentalomas: Diagnosis, Clinical Features, and Management

Simple Summary

A pituitary incidentaloma is a pituitary tumor or mass that is incidentally discovered in imaging studies which have been performed for reasons other than the symptoms of pituitary lesions. The majority of pituitary incidentalomas are pituitary neuroendocrine tumors (PitNETs) and Rathke cleft cysts. PitNETs have received attention because of their distinction from pituitary adenoma in the new World Health Organization (WHO) classification. The natural history of PitNETs is partially known, and the management of pituitary incidentalomas has been determined based on this history; however, the pathology of PitNETs has significantly changed with the new WHO classification, and studies with a high level of evidence are required to consider treatment guidelines for pituitary incidentalomas.

Abstract

Pituitary incidentalomas are tumors or mass lesions of the pituitary gland. These are incidentally discovered during imaging studies for symptoms that are not causally related to pituitary diseases. The most common symptom that triggers an examination is headache, and the most common type of pituitary incidentalomas are pituitary neuroendocrine tumors (PitNETs) and Rathke cleft cysts. The existing treatment strategy is controversial; however, surgical resection is recommended in cases of clinically non-functioning PitNETs with optic chiasm compression. In contrast, cystic lesions, such as Rathke cleft cysts, should be followed if the patients are asymptomatic. In this case, MRI and pituitary function tests are recommended every six months to one year; if there is no change, the follow-up period should be extended. The natural history of PitNET is partially known, and the management of pituitary incidentalomas is determined by this history. However, the pathogenesis of PitNET has significantly changed with the new World Health Organization classification, and follow-up is important based on this new classification. Therefore, a high level of evidence-based research is needed to consider treatment guidelines for pituitary incidentalomas in the future.

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

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

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.

The silent variants of pituitary tumors: demographic, radiological and molecular characteristics

INTRODUCTION

Tumors of the anterior pituitary gland (PTs) are mostly benign tumors with a low prevalence, which has nevertheless increased with advances in brain radiology techniques. Nearly half of PTs are not associated with a clinical endocrine syndrome. These tumors have been indistinctly named non-functioning pituitary adenomas (NFPAs) or silent pituitary tumors (SPTs) and the mechanisms of silencing are not fully known.

AIM

To study the frequency and characterize the silent variant of PTs in a large local series, and to assess their pituitary adenohypophyseal gene expression.

METHODS

This observational, cross-sectional study was performed in a Pituitary Tumor Center of Excellence and involved 268 PTs. After identifying the different subtypes according to the immunohistochemical (IHC) expression of adenohypophyseal hormones, we studied their gene expression by RT-qPCR.

RESULTS

We found that silent tumors were larger and more invasive, but not more proliferative than their functional counterparts. The RT-qPCR complements the IHC typification of PTs, reducing the proportion of null-cell subtype. Finally, some silent PT subtype variants showed lower specific adenohypophyseal hormone gene expression than their functional counterparts, which may contribute to the absence of endocrine manifestations.

CONCLUSIONS

This paper highlights the importance of identifying the silent variant of the PTs subtypes. As expected, silent tumors were larger and more invasive than their functioning counterparts. However, there was no difference in the proliferation activity between them. Finally, the lower specific gene expression in the silent than in the functioning counterparts of some PTs subtypes gives insights into the silencing mechanisms of PTs.

Long-Term Use of Temozolomide as Safe and Effective Therapy for an Aggressive Corticotroph Adenoma in a Very Old Patient

Background

Temozolomide (TMZ) is safe and effective in the treatment of aggressive pituitary adenomas (PAs). However, the optimal duration of TMZ therapy is still unknown. Moreover, data about administration of TMZ in elderly (≥65 years) people to treat aggressive PAs are scarce. We report the case of the oldest female patient undergoing the longest TMZ protocol described so far to treat an aggressive, initially silent corticotroph PA.

Case report

The patient initially underwent partial surgical removal of the PA. Subsequent treatment with cabergoline was applied, but it was unsuccessful in controlling the growth of the residual tumor. Pasireotide and external radiation also showed to be ineffective; therefore, treatment with TMZ was started at the standard dose of 200 mg/m²/day for 5 days every 4 weeks for a total of 47 cycles. At the time of treatment’s beginning, the patient was 83 years old. Radiological follow-up documented a progressive, remarkable reduction of the adenoma and the last imaging, after 39 cycles of TMZ, showed an intrasellar lesion with large areas of cystic degeneration. The patient also developed adrenal deficiency managed with glucocorticoid replacement. No major side effects were observed throughout the treatment, with exception of nausea, well controlled with anti-emetic medication. TMZ therapy was discontinued after 47 cycles; hormonal and imaging follow-up investigations documented sustained functional and dimensional response.

Conclusions

Our case supports the long-term use of TMZ, confirming its safety and efficacy also for elderly patients.

Aggressive pituitary tumors in the young and elderly

Aggressive pituitary tumors (APTs) represent rare pituitary adenomas (PAs) with local invasion of surrounding tissues, increased risk for multiple recurrence, rapid tumor growth, or resistance to standard therapies. The most common APTs in children and adolescents are giant prolactinomas and somatotropinomas. Few cases of Crooke's cell adenomas, silent corticotroph adenomas and pituitary carcinomas have also been reported in the literature. Pediatric patients with APTs have higher risk of harboring germline genetic defects, most commonly in the MEN1 and AIP genes. Since certain genetic defects confer a more aggressive behavior to PAs, genetic testing should be considered in tumors with young onset and positive family history. The management of pediatric APTs involves usually a combination of standard therapies (surgical, medical, radiation). Newer agents, such as temozolomide, have been used in few cases of pediatric pituitary tumors with promising results. In the elderly, PAs are more commonly non-functioning. Their management often poses dilemmas given the coexistence of age-related comorbidities. However, standard surgical treatment and temozolomide seem to be safe and well tolerated in elderly patients.

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.

Predictive modeling for pituitary adenomas: single center experience in 501 consecutive patients

BACKGROUND

Personalized postoperative management of patients with pituitary adenomas requires an early risk stratification system.

METHODS

We reviewed 501 cases operated between 10/27/2011 and 5/5/2016 by a single neurosurgeon. We determined biochemical remission and tumor resection at 3 months, and biochemical recurrence, tumor recurrence, radiation and reoperation during follow-up. We considered age, gender, tumor diameter, cavernous sinus invasion (CSI) by MRI, diagnostic category (clinical, biochemical and immunohistochemical), and proliferation markers in a Cox proportional hazards model. We built predictive models with the significant parameters and used Kaplan-Meier survival curves for time-dependent analyses.

RESULTS

The 501 cases comprised 141 functional and 360 nonfunctional adenomas. Tumor diameter, CSI, and ki-67 index predicted long-term events. Model 1 (CSI, diameter ≥ 2.9 cm and ki-67 > 3%) identified 18 (3.6%) adenomas and predicted persistent hypersecretory syndrome and residual tumor with 98.7% specificity (OR 8.6; CI 3.0-24.7). Model 2 (ki-67 > 3% and CSI) identified 48 (9.6%) adenomas and had 93.1% specificity (OR 3.3; CI 1.8-6.0). Model 3 (ki-67 > 3%, mitoses and p53, former "atypical" adenoma) identified 26 (5.2%) adenomas and had 96.0% specificity (OR 2.3; CI 1.0-5.0). Model 1 best predicted the long-term event-free survival and was strengthened when Knosp 3-4 CSI grades were used. Model 2 better identified the smaller adenomas at risk. Among the WHO 2017 special PA subtypes, patients with silent corticotroph adenoma had a lower event-free survival than ACTH-negative nonfunctional adenomas.

CONCLUSION

Use of CSI, ki-67 and tumor diameter in prediction models facilitates tailored surveillance and management of patients with pituitary adenomas.

Postoperative expression of Cushing disease in a young male: metamorphosis of silent corticotroph adenoma?

SUMMARY

Silent corticotroph adenoma (SCA) is an unusual type of nonfunctioning pituitary adenoma (NFA) that is silent both clinically and biochemically and can only be recognized by positive immunostaining for ACTH. Under rare circumstances, it can transform into hormonally active disease presenting with severe Cushing syndrome. It might often produce diagnostic dilemma with difficult management issue if not thoroughly investigated and subtyped accordingly following surgery. Here, we present a 21-year-old male who initially underwent pituitary adenomectomy for presumed NFA with compressive symptoms. However, he developed recurrent and invasive macroadenoma with severe clinical as well as biochemical hypercortisolism during post-surgical follow-up. Repeat pituitary surgery was carried out urgently as there was significant optic chiasmal compression. Immunohistochemical analysis of the tumor tissue obtained on repeat surgery proved it to be an aggressive corticotroph adenoma. Though not cured, he showed marked clinical and biochemical improvement in the immediate postoperative period. Anticipating recurrence from the residual tumor, we referred him for cyber knife radio surgery.

LEARNING POINTS

Pituitary NFA commonly present with compressive symptoms such as headache and blurred vision. Post-surgical development of Cushing syndrome in such a case could be either drug induced or endogenous. In the presence of recurrent pituitary tumor, ACTH-dependent Cushing syndrome indicates CD. Rarely a SCA presenting initially as NFA can transform into an active corticotroph adenoma. Immunohistochemical marker for ACTH in the resected tumor confirms the diagnosis.

Clinical Significance of Radical Surgery in the Treatment of Silent Corticotroph Adenoma

OBJECTIVE

Silent corticotroph adenomas (SCA) are endocrine-inactive pituitary adenomas with positive immunohistochemistry staining for adrenocorticotropic hormone (ACTH). We investigated whether SCA-associated clinical profiles were more aggressive than hormonally negative adenomas (HNA).

METHODS

Among 627 patients with pathologically proven endocrine-inactive pituitary adenomas between 2004 and 2013, positive immunohistochemistry revealed 55 SCAs and 411 HNAs. Surgical outcomes and radiological and endocrinological characteristics were compared.

RESULTS

Strong female predominance was observed in the SCA group (p<0.001). Cavernous sinus invasion was identified in 22 (40%) SCA patients and 72 (17.6%) HNA patients (p<0.001). There were no differences in ACTH or cortisol levels between the two groups. The incidence of preoperative hypopituitarism and postoperative hormonal outcome did not differ between two groups. Total resection was achieved in 35 patients (63.7%) with SCA and 332 patients (80.8%) with HNA (p=0.007). When tumors were completely removed, recurrence rates were not statistically different between two groups (p=0.60). When complete resection was not achieved, tumors regrew from these remnants in seven patients (35.0%) with SCA and 12 patients (15.2%) with HNA (p=0.05).

CONCLUSION

Total surgical resection for SCA is often challenging as these tumors frequently invade a cavernous sinus. Early remnant tumor intervention is justified, because untreated residual pituitary tumors regrow when patients were followed up for a long time. Prophylactic radiotherapy is not warranted for completely resected SCAs as tumor recurrence is uncommon.

CLINICALLY SILENT ADRENOCORTICOTROPIC HORMONE-SECRETING CROOKE CELL ADENOMA PRESENTING AS UNILATERAL EAR PAIN

Objective

Crooke cell adenoma (CCA) is a rare tumor of the anterior pituitary. It is highly aggressive and carries significant risk of morbidity and mortality.

Methods

This report focuses on the presentation of this disease process and review diagnosis and treatment. The patient is a 64-year-old male with a history of resected pituitary adenoma of unknown pathology.

Results

The patient underwent serial magnetic resonance imaging surveillance for numerous years without recurrence of tumor, however eventually developed symptoms of worsening left ear pain over 3 weeks that rapidly evolved to include ptosis. Imaging revealed a new pituitary macroadenoma. Urgent surgical resection revealed histopathological diagnosis of CCA. Corticotroph adenomas represent a rare subset of pituitary tumors. Clinically silent pituitary tumors demonstrate relatively higher rates of cavernous sinus invasion (30% versus 18%) and progression or recurrence (34% versus 6%) when compared to nonfunctioning adenomas. In CCA, only 65% of patients have clinical features of Cushing disease at presentation. Twenty-four-hour urinary free cortisol is discussed in the literature as a potential tool, where a value 4 times the upper limit of normal was predictive of higher risk of having Crooke cell changes. With a recurrence rate of up to 60%, multimodal treatment (surgery and radiation) is preferred.

Conclusion

This case highlights early detection and treatment as keys to reducing the risk of morbidity and mortality from CCA. Currently, there are limited tools for identifying patients who are high risk for developing Crooke cell changes. Treatment modalities classically include surgery and radiotherapy. Adjuvant and novel chemotherapies are being explored.

Histopathological classification of non-functioning pituitary neuroendocrine tumors

Non-functioning pituitary neuroendocrine tumors do not cause endocrine symptoms related to hypersecretion of adenohypophyseal hormones and are clinically characterized by symptoms due to growing sellar tumor mass. Histopathological classification of this tumor group has always been challenging due to their heterogeneity, limited knowledge on their biology, and diverse methodological problems. We have searched PubMed database for data related to the histopathological classification of non-functioning pituitary tumors and methods for its application. Principles of the classification and grading presented in the recently released 4th edition of the World Health Organization classification of endocrine tumors have been summarized. Based on the expression of anterior pituitary hormones and pituitary specific transcription factors, gonadotroph tumors dominate within the group of clinically non-functioning tumors, followed by corticotroph type; however, other less common types of the non-functioning tumors can be identified. Assessment of tumor cell proliferation is important to identify "high-risk adenomas." A few subtypes of non-functioning tumors belong to the category of potentially aggressive tumors, independent of the cell proliferation rate. Here, we present up to date criteria for the classification of clinically non-functioning pituitary tumors, offer a diagnostic approach for the routine clinical use, and emphasize a need for inclusion of prognostic and predictive markers in the classification.

Prognostic significance of corticotroph staining in radiosurgery for non-functioning pituitary adenomas: a multicenter study

Silent corticotroph staining pituitary adenoma (SCA) represents an uncommon subset of Non-Functioning adenomas (NFAs), hypothesized to be more locally aggressive. In this retrospective multicenter study, we investigate the safety and effectiveness of Stereotactic Radiosurgery (SRS) in patients with SCA compared with other non-SCA NFA's. Eight centers participating in the International Gamma-Knife Research Foundation (IGKRF) contributed to this study. Outcomes of 50 patients with confirmed SCAs and 307 patients with confirmed non-SCA NFA's treated with SRS were evaluated. Groups were matched. SCA was characterized by a lack of clinical evidence of Cushing disease, yet with positive immunostaining for corticotroph. Median age was 55.2 years (13.7-87). All patients underwent at least one trans-sphenoidal tumor resection prior to SRS. SRS parameters were comparable as well. Median follow-up 40 months (6-163). Overall tumor control rate (TCR) 91.2% (n = 280). In the SCA group, TCR were 82% (n = 41) versus 94.1% (n = 289) for the control-NFA (p = 0.0065). The SCA group showed a significantly higher incidence of new post-SRS visual deficit (p < 0.0001) assigned to tumor progression and growth, and post-SRS weakness and fatigue (p < 0.0001). In univariate and multivariate analysis, only the status of silent corticotroph staining (p = 0.005, p = 0.009 respectively) and margin dose (p < 0.0005, p = 0.0037 respectively) significantly influenced progression rate. A margin dose of ≥17 Gy was noted to influence the adenoma progression rate in the entire cohort (p = 0.003). Silent corticotroph staining represents an independent factor for adenoma progression and hypopituitarism after SRS. A higher margin dose may convey a greater chance of TCR.

Overview of the 2017 WHO Classification of Pituitary Tumors

This review focuses on discussing the main changes on the upcoming fourth edition of the WHO Classification of Tumors of the Pituitary Gland emphasizing histopathological and molecular genetics aspects of pituitary neuroendocrine (i.e., pituitary adenomas) and some of the non-neuroendocrine tumors involving the pituitary gland. Instead of a formal review, we introduced the highlights of the new WHO classification by answering select questions relevant to practising pathologists. The revised classification of pituitary adenomas, in addition to hormone immunohistochemistry, recognizes the role of other immunohistochemical markers including but not limited to pituitary transcription factors. Recognizing this novel approach, the fourth edition of the WHO classification has abandoned the concept of "a hormone-producing pituitary adenoma" and adopted a pituitary adenohypophyseal cell lineage designation of the adenomas with subsequent categorization of histological variants according to hormone content and specific histological and immunohistochemical features. This new classification does not require a routine ultrastructural examination of these tumors. The new definition of the Null cell adenoma requires the demonstration of immunonegativity for pituitary transcription factors and adenohypophyseal hormones Moreover, the term of atypical pituitary adenoma is no longer recommended. In addition to the accurate tumor subtyping, assessment of the tumor proliferative potential by mitotic count and Ki-67 index, and other clinical parameters such as tumor invasion, is strongly recommended in individual cases for consideration of clinically aggressive adenomas. This classification also recognizes some subtypes of pituitary neuroendocrine tumors as "high-risk pituitary adenomas" due to the clinical aggressive behavior; these include the sparsely granulated somatotroph adenoma, the lactotroph adenoma in men, the Crooke's cell adenoma, the silent corticotroph adenoma, and the newly introduced plurihormonal Pit-1-positive adenoma (previously known as silent subtype III pituitary adenoma). An additional novel aspect of the new WHO classification was also the definition of the spectrum of thyroid transcription factor-1 expressing pituitary tumors of the posterior lobe as representing a morphological spectrum of a single nosological entity. These tumors include the pituicytoma, the spindle cell oncocytoma, the granular cell tumor of the neurohypophysis, and the sellar ependymoma.

Increased expression of the microRNA 106b~25 cluster and its host gene MCM7 in corticotroph pituitary adenomas is associated with tumor invasion and Crooke's cell morphology

PURPOSE

MCM7 (minichromosome maintenance complex component 7), a DNA replication licensing factor, is a host gene for the oncogenic miR-106b~25 cluster. It has been recently revealed as a relevant prognostic biomarker in a variety of cancers, including pituitary adenomas. The purpose of this study was to assess whether miR-106b~25 and MCM7 levels correlate with tumor invasiveness in a cohort of ACTH-immunopositive adenomas.

METHODS

Tissue samples were obtained intraoperatively from 25 patients with pituitary adenoma. Tumor invasiveness was assessed according to the Knosp grading scale. MCM7, Ki-67 and TP53 levels were assessed by immunohistochemical staining, while the expression of miR-106b-5p, miR-93-5p, miR-93-3p and miR-25-3p were measured using quantitative real-time PCR performed on RNA isolated from FFPE tissues.

RESULTS

We have found a significant increase in MCM7 and Ki-67 labeling indices in invasive ACTHomas. Moreover, MCM7 was ubiquitously overexpressed in Crooke's cell adenomas. The expression of miR-93-5p was significantly elevated in invasive compared to noninvasive tumors. In addition, all four microRNAs from the miR-106b~25 cluster displayed marked upregulation in Crooke's cell adenomas. Remarkably, MCM7 and miR-106b-5p both strongly correlated with Knosp grade. A combination of MCM7 LI and miR-106b~25 cluster expression was able to accurately differentiate invasive from noninvasive tumors and had a significant discriminatory ability to predict postoperative tumor recurrence/progression.

CONCLUSIONS

miR-106b~25 and its host gene MCM7 are potential novel biomarkers for invasive ACTH-immunopositive pituitary adenomas. Additionally, they are both significantly upregulated in rare Crooke's cell adenomas and might therefore contribute to their aggressive phenotype.

Silent Crooke's cell corticotroph adenoma of the pituitary gland presenting as delayed puberty

Summary

Corticotroph adenomas are extremely rare in children and adolescents. We present a 15-year-old boy who was investigated for delayed puberty (A1P2G1, bilateral testicular volumes of 3 mL each). There was no clinical or laboratory evidence suggestive of chronic illness, and the initial clinical impression was constitutional delay in puberty. Subsequently, MRI scan of the brain revealed the presence of a mixed cystic and solid pituitary lesion slightly displacing the optic chiasma. The lesion was removed by transphenoidal surgery and the biopsy confirmed the lesion to be pituitary adenoma. Furthermore, the adenoma cells also had Crooke’s hyaline changes and were intensely positive for ACTH. However there was no clinical/biochemical evidence of ACTH excess. There was a spontaneous pubertal progression twelve months after the surgery (A2P4G4, with bilateral testicular volume of 8 mL). Crooke’s cell adenoma is an extremely rare and aggressive variant of corticotroph adenoma that can uncommonly present as a silent corticotroph adenoma in adults. We report for the first time Crooke’s cell adenoma in an adolescent boy presenting with delayed puberty.

Learning points:

Silent subtype 3 pituitary adenomas are not always silent and represent poorly differentiated monomorphous plurihormonal Pit-1 lineage adenomas

Originally classified as a variant of silent corticotroph adenoma, silent subtype 3 adenomas are a distinct histologic variant of pituitary adenoma of unknown cytogenesis. We reviewed the clinical, biochemical, radiological, immunohistochemical and ultrastructural features of 31 silent subtype 3 adenomas to clarify their cellular origin. Among 25 with clinical and/or radiological data, all were macroadenomas; there was cavernous sinus invasion in 30% of cases and involvement of the clivus in 17% of cases. Almost 90% of patients were symptomatic; 67% had mass effect symptoms, 37% were hypogonadal and 8% had secondary adrenal insufficiency. Significant hormonal excess in 29% of cases included hyperthyroidism in 17%, acromegaly in 8% and hyperprolactinemia above 150 μg/l in 4%. Two individuals with hyperprolactinemia who were younger than 30 years had multiple endocrine neoplasia type 1. Immunohistochemically, all 31 tumors were diffusely positive for the pituitary lineage-specific transcription factor Pit-1. Although three only expressed Pit-1, others revealed variable positivity for one or more hormones of Pit-1 cell lineage (growth hormone, prolactin, thyroid-stimulating hormone), as well as alpha-subunit and estrogen receptor. Most tumors exhibited perinuclear reactivity for keratins with the CAM5.2 antibody; scattered fibrous bodies were noted in five (16%) tumors. The mean MIB-1 labeling index was 4% (range, 1-9%). Fourteen cases examined by electron microscopy were composed of a monomorphous population of large polygonal or elongated cells with nuclear spheridia. Sixty-five percent of patients had residual disease after surgery; after a mean follow-up of 48.4 months (median 41.5; range=2-171) disease progression was documented in 53% of those cases. These data identify silent subtype 3 adenomas as aggressive monomorphous plurihormonal adenomas of Pit-1 lineage that may be associated with hyperthyroidism, acromegaly or galactorrhea and amenorrhea. Our findings argue against the use of the nomenclature 'silent' for these tumors. To better reflect the characteristics of these tumors, we propose that they be classified as 'poorly differentiated Pit-1 lineage adenomas'.

Retrospective observational analysis of non-irradiated non-functioning pituitary adenomas

PURPOSE

The management of choice of non-functioning pituitary adenomas (NFPAs) remains debulking surgery when symptomatic. However, patient series systematically reporting the NFPAs outcome that were not treated either surgically, medically or with radiotherapy during long follow-up thereby giving an indication of their natural history are limited. Aim of the present study was to evaluate the natural course of presumed NFPAs, the outcome of confirmed NFPAs during a long follow-up period.

METHODS

Between 1993 and 2013, 84 patients with presumed NFPA were studied retrospectively. Patients were enrolled based on the following criteria: imaging suggestive of pituitary adenoma, absence of any biochemical/clinical evidence of hormonal excess, exclusion of prolactinomas and at least one sequential imaging during the follow-up. Repeated assessment of the pituitary function, visual fields and imaging was performed at regular intervals. The follow-up duration was evaluated from the first and last imaging dates.

RESULTS

In group F (follow-up without surgery, 33 patients), the macroadenomas showed a 15% probability of tumor growth and reduction. Similar tumor size alterations were observed also for the microadenomas. In group S (surgery, 51 patients), both residual tumors (>1 and <1 cm) following initial surgical resection remain mainly stable until the last imaging.

CONCLUSIONS

Based on the given lack of approved medical treatment and the possible risks of surgical intervention in presence of significant comorbidities, our study proposes a conservative approach with a careful follow-up in patients with NFPAs without visual or neurological abnormalities.

Complications after transsphenoidal surgery for patients with Cushing's disease and silent corticotroph adenomas

OBJECT The purpose of this study was to describe complications associated with the endonasal, transsphenoidal approach for the treatment of adrenocorticotropic hormone (ACTH)-positive staining tumors (Cushing's disease [CD] and silent corticotroph adenomas [SCAs]) performed by 1 surgeon at a high-volume academic medical center. METHODS Medical records from Brigham and Women's Hospital were retrospectively reviewed. Selected for study were 82 patients with CD who during April 2008-April 2014 had consecutively undergone transsphenoidal resection or who had subsequent pathological confirmation of ACTH-positive tumor staining. In addition to demographic, patient, tumor, and surgery characteristics, complications were evaluated. Complications of interest included syndrome of inappropriate antidiuretic hormone secretion, diabetes insipidus (DI), CSF leakage, carotid artery injury, epistaxis, meningitis, and vision changes. RESULTS Of the 82 patients, 68 (82.9%) had CD and 14 (17.1%) had SCAs; 55 patients were female and 27 were male. Most common (n = 62 patients, 82.7%) were microadenomas, followed by macroadenomas (n = 13, 14.7%). A total of 31 (37.8%) patients underwent reoperation. Median follow-up time was 12.0 months (range 3-69 months). The most common diagnosis was ACTH-secreting (n = 68, 82.9%), followed by silent tumors/adenomas (n = 14, 17.1%). ACTH hyperplasia was found in 8 patients (9.8%). Of the 74 patients who had verified tumors, 12 (16.2%) had tumors with atypical features. The overall (CD and SCA) rate of minor complications was 35.4%; the rate of major complications was 8.5% (n = 7). All permanent morbidity was associated with DI (n = 5, 6.1%). In 16 CD patients (23.5%), transient DI developed. Transient DI was more likely to develop in CD patients who had undergone a second operation (37.9%) than in those who had undergone a first operation only (12.8%, p < 0.05). Permanent DI developed in 4 CD patients (5.9%) and 1 SCA patient (7.1%). For 1 CD patient, intraoperative carotid artery injury required endovascular sacrifice of the injured artery, but the patient remained neurologically intact. For another CD patient, aseptic meningitis developed and was treated effectively with corticosteroids. One CD patient experienced major postoperative epistaxis requiring another operative procedure to achieve hemostasis. For 2 CD patients, development of sinus mucoceles was managed conservatively. For 1 SCA patient, an abdominal wound dehisced at the fat graft site. No patients experienced postoperative CSF leakage, visual impairment, or deep vein thrombosis. CONCLUSIONS Transsphenoidal surgery is the treatment of choice for patients with CD and other ACTH-positive staining tumors. Recent advances in endoscopic technology and increasing surgeon comfort with this technology are making transsphenoidal procedures safer, faster, and more effective. Serious complications are uncommon and can be managed successfully.

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.

Screening for ACTH-dependent hypercortisolism in patients affected with pituitary incidentaloma

CONTEXT

Pituitary incidentalomas (PIs) are commonly encountered in clinical practice. The management of these asymptomatic pituitary lesions is still controversial. Systematic screening for subclinical or mild ACTH-dependent hypercortisolism (AH) is not presently recommended, due to the limited data available thus far on the epidemiological and clinical relevance of this condition in patients with PIs. As subclinical hypercortisolism (SH) was considered to be associated with chronic complications of overt cortisol excess, such as hypertension, diabetes, and osteoporosis, this disorder should be diagnosed at the early stage.

OBJECTIVE

The objective of this study was to evaluate the prevalence of hypercortisolism in a population of subjects with PIs.

DESIGN, SUBJECTS, AND METHODS

A total of 68 consecutive patients (48 females and 20 males, aged 18-82 years) without clinically overt hypercortisolism, who were referred for evaluation of PIs between January 2010 and March 2013, were prospectively investigated for AH. Pituitary hypercortisolism was diagnosed in the presence of cortisol >50 nmol/l after 1 mg dexamethasone suppression test, non-suppressed ACTH, and the additional finding of one of the following: urinary free cortisol (UFC) >193 nmol/24 h, and midnight serum and salivary cortisol levels >207 and 2.8 nmol/l respectively.

RESULTS

Among patients with PIs, we found a 7.3% rate of pituitary hypercortisolism diagnosed with biochemical criteria and a 4.4% rate of histologically confirmed AH.

CONCLUSIONS

Subclinical or mild hypercortisolism may be more common than generally perceived in patients with PIs.

Clinical characteristics and treatment outcome of 485 patients with nonfunctioning pituitary macroadenomas

Background. Nonfunctioning pituitary adenomas (NFPAs) are the most common benign lesions of the pituitary gland. Objective. To describe our experience with the management of NFPA. Study Design and Methods. Retrospective evaluation of NFPA patients managed between 2008 and 2013. We analyzed data regarding clinical presentation, imaging diagnosis, hormonal status, surgical, radiotherapeutic, and pharmacological treatment, and outcome. Results. 485 patients (54% men, mean age 53 ± 14 years) were followed for a median of 6.5 years. Visual field abnormalities and headaches were the presenting complaints in 87% and 66%, respectively. The diagnosis of NFPA was made incidentally in 6.2%, and 8% presented with clinical evidence of apoplexy. All patients harbored macroadenomas, with a median volume of 10306 mm(3); 57.9% had supra- or parasellar invasion and 19.6% had tumors larger than 4 cm. Central hypothyroidism, hypogonadism, and hypocortisolism were present in 47.2%, 35.9%, and 27.4%, respectively. Surgical resection was performed at least once in 85.7%. Tumor persistence was documented in 27% and was related to the size and invasiveness of the lesion. In selected cases, radiotherapy proved to be effective in controlling or preventing tumor growth. Conclusions. The diagnosis and treatment of NFPA are complex and require a multidisciplinary approach.

Aggressive pituitary adenomas--diagnosis and emerging treatments

The WHO categorizes pituitary tumours as typical adenomas, atypical adenomas and pituitary carcinomas, with typical adenomas constituting the major class. However, the WHO classification does not provide an accurate correlation between histopathological findings and clinical behaviour. Tumours lacking typical histological features are classified as atypical, but not all are clinically atypical or exhibit aggressive behaviour. Pituitary carcinomas, by definition, have craniospinal or systemic metastases, although not all display classical cytological features of malignancy. Aggressive pituitary adenomas, defined from a clinical perspective, have earlier and more frequent recurrences and can be resistant to conventional treatments. Specific biomarkers have not yet been identified that can distinguish between clinically aggressive and nonaggressive pituitary adenomas, although the antigen Ki-67 proliferation index might be of value. This Review highlights the need to develop new biomarkers to facilitate the early detection of clinically aggressive pituitary adenomas and discusses emerging markers that hold promise for their identification. Defining aggressiveness is of crucial importance for improving the management of patients by enhancing prognostic predictions and effectiveness of treatment. New drugs, such as temozolomide, have potential use in the management of these patients; anti-VEGF therapy, mTOR and tyrosine kinase inhibitors are also potentially useful in managing selected patients.

The role of mediators of cell invasiveness, motility, and migration in the pathogenesis of silent corticotroph adenomas

Silent corticotroph adenomas (SCAs) represent a distinct subset of clinically non-functioning pituitary adenomas. There are two variants of SCA; type I are densely granulated basophilic tumors and type II are sparsely granulated and chromophobic tumors. SCAs are known to be aggressive than the more common non-functioning gonadotroph adenomas (NFGAs). Cell-matrix interactions play an important role in the pathogenesis of pituitary adenomas. In this study, we compared 19 SCAs and 50 NFGAs with known fibroblast growth factor receptor-4 (FGFR4) status using semi-quantitative immunohistochemistry to localize β1-integrin, osteopontin, and matrix metalloproteinase-1 (MMP-1) as cytoplasmic, membranous, or mixed cytoplasmic-membranous staining to achieve scores of 1-4. Staining for β1-integrin was significantly higher in SCAs (100 %, score 3.3) than in NFGAs (96 %; score 2.6) (p = 0.0482); there was no statistical difference within subgroups of SCA (type II score 3.4; type I score 2.8) (p = 0.2663). Osteopontin immunoreactivity was also higher in SCAs (100 %, score 3.7) than in NFGAs (42 %, score 0.8) (p = 0.0001); there was no statistical difference within subgroups of SCA (type II score 3.6; type I score 3.9) (p = 0.2787). In contrast, MMP-1 immunoreactivity was lower in SCAs (89 %; score 2.5) than in NFGAs (98 %; score 3.6) (p = 0.0005); there was no statistical difference within subgroups of SCA (type II score 2.7; type I score 2.0) (p = 0.30704). The MMP-1 results correlated with FGFR4 expression (NFGA 96 %, type II SCA 71 %, type I SCA 40 %). Our data indicate that the biological aggressivity of SCAs compared with NFGA may be due to high osteopontin expression; in contrast, high MMP-1 is characteristic of NFGAs that also express more FGFR4. Further investigations are warranted to clarify the underlying regulatory mechanisms of these markers. The high osteopontin or FGFR4/MMP-1 expression levels in SCAs and NFGAs, respectively, indicate the potential for therapeutic strategies targeting osteopontin or FGFR4/MMP-1 for inoperable tumors of these types.

Diagnosis and Multimodality Management of Cushing's Disease: A Practical Review

Cushing's Disease is caused by oversecretion of ACTH from a pituitary adenoma and results in subsequent elevations of systemic cortisol, ultimately contributing to reduced patient survival. The diagnosis of Cushing's Disease frequently involves a stepwise approach including clinical, laboratory, neuroimaging, and sometimes interventional radiology techniques, often mandating multidisciplinary collaboration from numerous specialty practitioners. Pituitary microadenomas that do not appear on designated pituitary MRI or dynamic contrast protocols may pose a particularly challenging subset of this disease. The treatment of Cushing's Disease typically involves transsphenoidal surgical resection of the pituitary adenoma as a first-line option, yet may require the addition of adjunctive measures such as stereotactic radiosurgery or medical management to achieve normalization of serum cortisol levels. Vigilant long-term serial endocrine monitoring of patients is imperative in order to detect any recurrence that may occur, even years following initial remission. In this paper, a stepwise approach to the diagnosis, and various management strategies and associated outcomes in patients with Cushing's Disease are discussed.

Subclinical hyperfunctioning pituitary adenomas: the silent tumors

Pituitary adenomas are classified by function as defined by clinical symptoms and signs of hormone hypersecretion with subsequent confirmation on immunohistochemical staining. However, positive immunostaining for pituitary cell types has been shown for clinically nonfunctioning adenomas, and this entity is classified as silent functioning adenoma. Most common in these subtypes include silent gonadotroph adenomas, silent corticotroph adenomas and silent somatotroph adenomas. Less commonly, silent prolactinomas and thyrotrophinomas are encountered. Appropriate classification of these adenomas may affect follow-up care after surgical resection. Some silent adenomas such as silent corticotroph adenomas follow a more aggressive course, necessitating closer surveillance. Furthermore, knowledge of the immunostaining characteristics of silent adenomas may determine postoperative medical therapy. This article reviews the incidence, clinical behavior, and pathologic features of clinically silent pituitary adenomas.

Clinical factors involved in the recurrence of pituitary adenomas after surgical remission: a structured review and meta-analysis

To study the currently available data of recurrence rates of functioning and nonfunctioning pituitary adenomas following surgical cure and to analyze associated predisposing factors, which are not well established. A systematic literature search was conducted using Medline, Embase, Web of Science and the Cochran Library for studies reporting data on recurrence of pituitary adenoma after surgery, in nonfunctioning adenoma (NF), prolactinoma (PRL) acromegaly (ACRO) and Cushing's disease (CUSH). Of 557 initially retrieved potential relevant studies 143 were selected. Recurrence in NFA was defined as reappearance of tumor on MRI or CT. Increase of hormone levels above normal limits as set by the authors after initial remission was used to indicate recurrence in the functioning tumor types. Remission percentage was lowest in NFA compared with other tumor types (P < 0.001). Surgery-related hypopituitarism was more frequent in CUSH than in the other tumors (P < 0.001). Recurrence, expressed as percentage of the cured population or as ratio of recurrence and total patient years of follow-up was highest in PRL (P < 0.001). The remission percentage did not improve over 3 decades of publications, but there was a modest decrease in recurrence rate (P = 0.04). Recurrences peaked between 1 and 5 years after surgery. Most of the studies with a sufficient number of recurrences did not apply multivariate statistics, and mentioned at best associated factors. Age, gender, tumor size and invasion were generally unrelated to recurrence. For functioning adenomas a low postoperative hormone concentration was a prognostically favorable factor. In NFA no specific factor predicted recurrence. Recurrence rate differs between pituitary adenomas, being highest in patients with prolactinoma, with the highest incidence of recurrence between 1 and 5 years after surgery in all adenomas. Patients with NFA have a lower chance of remission than patients with functioning adenomas. The postoperative basal hormone level is the most important predictor for recurrence in functioning adenomas, while in NFA no single convincing factor could be identified.

Silent corticogonadotroph adenomas: clinical and cellular characteristics and long-term outcomes

Silent corticotrophins adenomas (SCAs) are clinically silent and non-secreting but immunostain positively for ACTH. We hypothesize that SCAs comprise both corticotroph and gonadotroph characteristics. Cohort analysis from 1994-2008 with follow-up time ranging from 1-15 years in a tertiary referral center. We compared preoperative and postoperative clinical results and tumor cytogenesis in 25 SCAs and 84 nonfunctioning adenomas in 109 consecutive patients diagnosed pre-operatively with nonfunctioning pituitary adenomas. Clinical outcomes were radiologic and hormonal measures. Pathologic outcomes were expression of relevant pituitary hormones, tissue-specific transcription factors, and electron microscopy features. Preoperative SCA presentation was similar to that observed for nonfunctioning adenomas. However, SCAs recurred postoperatively at a median of 3 years vs. 8 years for nonfunctioning adenomas (p<0.0001). Fifty-four percent of patients with SCAs had new onset postoperative hypopituitarism vs. 17% of nonfunctioning adenomas (p<0.025). SCAs (n=18) were immunopositive for ACTH, cytoplasmic and nuclear SF-1, NeuroD1, DAX-1, and alpha-gonadotropin subunit, but Tpit negative, and co-expression of tumor ACTH with either SF-1 or LH was detected. In contrast, functional corticotroph adenomas (n=11) were immunopositive for ACTH, nuclear SF-1, NeuroD1, and Tpit, but negative for DAX-1, a gonadotroph cell transcription factor. Gonadotroph adenomas (n=23) were immunonegative for ACTH and Tpit but positive for nuclear SF-1, NeuroD1, and DAX-1. SCA electron microscopy demonstrated ultrastructural features consistent with corticotroph and gonadotroph cells. As SCAs exhibit features consistent with both corticotroph and gonadotroph cytologic origin, we propose a pathologic and clinically distinct classification of SCAs as silent corticogonadotroph adenomas.

The role of radiation therapy in the management of non-functioning pituitary adenomas

Surgical removal of non-functioning pituitary adenoma (NFPA) is the first-choice therapeutic option, but radical removal of the tumor cannot be accomplished in all patients. The best strategy to prevent regrowth of NFPA is still a matter of debate. Adjuvant radiotherapy is very effective in reducing recurrence rate after incomplete removal of NFPA, but concerns still exist about long-term toxicity of radiation. Different modalities have been developed to irradiate the pituitary region. One major distinction is between radiation techniques that deliver the total dose in multiple sessions using 3 fixed radiation beams and radiosurgical equipment that delivers the total dose to the target volume in a single treatment session. Progression-free survival of patients with NFPA treated by adjuvant radiotherapy is well above 90% at 5 yr in most studies and diminishes only slightly at 10 yr. Very few studies have a more prolonged follow-up. In comparison, the 5- and 10-yr estimated recurrence rate without adjuvant radiotherapy ranged from 15% to 51% and from 44% to 78%, respectively. Complications of radiation include rare but severe side-effects, such as secondary brain neoplasm, optic neuropathy, cerebrovascular accidents, and more frequent but less severe complications, such as pituitary deficiency. Optimal management of patients with residual or recurring NFPA after surgical debulking can be achieved through the judicious use of different treatment options, necessitating close cooperation between neurosurgeons, endocrinologists, and radiation oncologists.

Symptomatic cystic degeneration of a clinically silent corticotroph tumor of the pituitary gland

Clinically silent corticotroph tumors of the pituitary gland are those tumors that stain for adrenocorticotropic hormone (ACTH) but do not manifest with clinical or laboratory features of Cushing disease. These tumors have been described as exhibiting more aggressive behavior than other nonfunctional pituitary tumors. We present an unusual case of a clinically silent corticotropic adenoma of the pituitary gland that underwent cystic degeneration following recurrence after transsphenoidal surgery and radiation therapy. The patient underwent left frontotemporal craniotomy with resection of the suprasellar mass and decompression of the left optic nerve. Postoperative magnetic resonance imaging demonstrated no further optic chiasm or nerve compression. Patients with clinically silent ACTH-secreting tumors should be monitored for aggressive tumor behavior and may require closer follow-up than those patients harboring other nonfunctional tumors.

The postoperative monitoring of nonfunctioning pituitary adenomas

Clinically nonfunctioning pituitary tumors are common in tertiary endocrine practice. Although it is widely accepted that patients with these adenomas require long-term surveillance after surgery-particularly those with macroadenomas, which grow much more frequently than microadenomas-a consensus on postoperative monitoring and treatment strategies is lacking. The indications for radiotherapy, which has seen a decline in use over the past decade, are not clear, although most experts would agree that residual tumor mass after surgery, as well as tumor expansion into the cavernous sinus, indicate the need to consider postoperative radiotherapy. In patients not treated with radiotherapy after surgical treatment of a nonfunctioning adenoma, MRI of the tumor should be performed annually for the first 6 years and every 2 years thereafter. In addition, silent adrenocorticotropic hormone-secreting tumors can behave more aggressively if they recur, and tumor regrowth can also occasionally be found in patients after classical pituitary apoplexy, which suggests that individuals with these conditions should also be monitored carefully after surgery. However, at which point this scanning routine can be ceased remains the subject of debate, as few data on late recurrence of nonfunctioning pituitary adenomas exist.

Atypical pituitary adenomas: incidence, clinical characteristics, and implications

Object

The 2004 WHO classification of pituitary adenomas now includes an “atypical” variant, defined as follows: MIB-1 proliferative index greater than 3%, excessive p53 immunoreactivity, and increased mitotic activity. The authors review the incidence of this atypical histopathological subtype and its correlation with tumor subtype, invasion, and surgical features.

Methods

The records of 121 consecutive patients who underwent transsphenoidal surgery for pituitary adenomas during an 18-month period were retrospectively reviewed for evidence of atypical adenomas.

Results

Eighteen adenomas (15%) met the criteria for atypical lesions; 17 (94%) of the 18 were macroadenomas. On imaging, 15 (83%) demonstrated imaging evidence of surrounding invasion, compared with 45% of typical adenomas (p = 0.004). Atypical tumors occurred in 12 female (67%) and 6 male (33%) patients. Patient age ranged from 16 to 70 years (mean 48 years). Nine patients (50%) had hormonally active tumors, and 9 had nonfunctional lesions. Four (22%) of the 18 patients presented to us with recurrent tumors. Immunohistochemical analysis demonstrated the following tumor subtypes: GH-secreting adenoma with plurihormonal staining (5 patients [28%]); null-cell adenoma (5 patients [28%]); silent ACTH tumor (3 patients [17%]), ACTH-staining tumor with Cushing's disease (2 patients [11%]), prolactinoma (2 patients [11%]), and silent FSH-staining tumor (1 patient [6%]). The MIB-1 labeling index ranged from 3% to 20% (mean 7%).

Conclusions

Atypical tumors were identified in 15% of resected pituitary adenomas, and they tended to be aggressive, invasive macroadenomas. More longitudinal follow-up is required to determine whether surgical outcomes, potential for recurrence, or metastasis of atypical adenomas vary significantly from their typical counterparts.

Isolated sixth cranial nerve palsy as the presenting symptom of a rapidly expanding ACTH positive pituitary adenoma: a case report

Background

Pituitary adenoma may present with neuro-ophthalmic manifestations and, typically, rapid tumor expansion is the result of apoplexy. Herein, we present the first case of an isolated sixth cranial nerve palsy as initial feature of a rapidly expanding ACTH positive silent tumor without apoplexy.

Case Presentation

A 44 year old female with a history of sarcoidosis presented with an isolated sixth cranial nerve palsy as the initial clinical feature of a rapidly expanding ACTH positive silent pituitary adenoma. The patient underwent emergent transsphenoidal hypophysectomy for this rapidly progressive tumor and subsequently regained complete vision and ocular motility. Despite tumor extension into the cavernous sinus, the other cranial nerves were spared during the initial presentation.

Conclusions

This case illustrates the need to consider a rapidly growing pituitary tumor as a possibility when presented with a rapidly progressive ophthalmoplegia.

Pituitary apoplexy in an adrenocorticotropin-producing pituitary macroadenoma

Adrenocorticotropin (ACTH) producing macroadenomas and pituitary apoplexy are unusual in Cushing' s disease. A 20-year-old man who had been diagnosed Cushing' s disease 2 months ago, presented with sudden headache, nausea, and vomiting. His serum cortisol level was 0.4 μg/dl and ACTH level was 23.9 pg/ml. Magnetic resonance imaging of the pituitary gland disclosed a hemorrhage in the pituitary macroadenoma (22×19 mm). He was treated with IV methylprednisolone immediately and then the symptoms were relieved within the first day of the treatment. The hemorrhagic lesion was resected by transsphenoidal surgery successfully. Impaired secretion of pituitary hormones may be seen after the pituitary apoplexy. We communicate a case with pituitary apoplexy of an ACTH secreting pituitary macroadenoma, causing acute glucocorticoid insufficiency.

Clinical, hormonal and molecular characterization of pituitary ACTH adenomas without (silent corticotroph adenomas) and with Cushing's disease

OBJECTIVE

Silent corticotroph adenomas (SCAs) are rare pituitary tumours immunoreactive for ACTH, but without clinical evidence of Cushing's disease. We characterized SCAs based on clinical, hormonal and molecular data, and compared the characteristics of these tumours with those of macro (MCA)- and micro (mCA)-ACTH adenomas with Cushing's disease.

METHODS

Fifty ACTH adenomas (14 SCAs, 15 MCAs and 21 mCAs) with complete corresponding clinical, radiological and biochemical data were selected. Histological corticotroph differentiation; immunostaining for ACTH, beta-endorphin and beta-LPH; and mRNA expression levels of TPIT, POMC, GRalpha, prohormone convertase 1/3 (PC1/3) and galectin-3 were compared in 21 representative tumours.

RESULTS

Despite the absence of clinical hypercortisolism in patients with SCA, elevated plasma ACTH levels that were similar to those associated with mCA were observed. The cortisol/ACTH ratio was similar between SCA and MCA groups and lower than that found with mCA (P<0.05). This dissociation could be explained by lower expression of PC1/3 in SCA and MCA than in mCA (P<0.05). After an i.v. dexamethasone suppression test, ACTH levels were significantly higher in patients with MCA than in those with mCA (P<0.05). Cytological and immunocytochemical analyses as well as mRNA expression levels of TPIT, POMC and GRalpha confirmed corticotroph differentiation in both mCAs and MCAs and in half of the SCAs, with a strong correlation between TPIT and POMC mRNA expression levels in SCAs (R(2)=0.72; P<0.01) and in MCAs (R(2)=0.65; P<0.05).

CONCLUSIONS

Despite the absence of hypercortisolism, SCAs exhibit histological, biochemical and molecular corticotroph differentiation. SCA and MCA show hormonal and molecular similarities differentiating them from mCA.

Long-term recurrence and mortality after surgery and adjuvant radiotherapy for nonfunctional pituitary adenomas

OBJECT

Long-term outcomes following surgery for nonfunctional pituitary adenomas (NFPAs) are unclear. The role of adjuvant radiation therapy is therefore controversial because it is associated with higher tumor control but also carries known long-term morbidity. The authors' aim was to determine predictors of recurrence and overall survival and to define patient subgroups that may benefit from radiotherapy.

METHODS

The authors performed a retrospective cohort analysis of 663 patients who underwent surgery between 1975 and 1995 for treatment of primary NFPAs. The main outcome measures were disease progression after surgery, defined by clinical and/or imaging criteria, and all-cause mortality.

RESULTS

Over a median clinical follow-up of 8.4 years, there were 64 (9.7%) recurrences after treatment, with a median time to recurrence of 5.6 years. The 5-, 10-, and 15-year recurrence-free probabilities were 0.93, 0.87, and 0.81, respectively. Multivariate Cox proportional hazard regression analysis identified the following predictors as associated with increased recurrence: cavernous sinus invasion (hazard ratio [HR] 3.6, 95% confidence interval [CI] 1.5-6.4; p < 0.001) and subtotal resection (STR) without radiotherapy (HR 3.6, 95% CI 1.4-14; p = 0.01). Using time-to-event estimates to adjust for differences in follow-up between groups, radiotherapy was found to reduce tumor recurrence in only those patients who received an STR (p < 0.001, log-rank test) but not gross-total resection (GTR; p = 0.63, log-rank test). Median follow-up for overall survival was 14.0 years. The 5-, 10-, 15- and 20-year overall survival estimates were 0.91, 0.81, 0.69, and 0.55, respectively. Within the study cohort and in age- and sex-adjusted comparison with the general US population, increased relative mortality was observed in patients who underwent radiotherapy or STR.

CONCLUSIONS

Cavernous sinus invasion is an important prognostic variable for long-term control of NFPAs. Radiotherapy results in long-term tumor control for patients who undergo STR but does not affect recurrence rates and may increase the risk of death after GTR. Given the risks associated with radiotherapy, there is no role for its routine application in patients who have undergone GTR of their NFPA. In all patients, long-term monitoring is required.

Early results of surgery in patients with nonfunctioning pituitary adenoma and analysis of the risk of tumor recurrence

OBJECT

Nonfunctioning pituitary adenomas (NFPAs) are benign tumors of the pituitary gland that typically cause visual and/or hormonal dysfunction. Surgery is the treatment of choice, but patients remain at risk for tumor recurrence for several years afterwards. The authors evaluate the early results of surgery and the long-term risk of tumor recurrence in patients with NFPAs.

METHODS

Between 1990 and 2005, 491 previously untreated patients with NFPA underwent surgery at the Università Vita-Salute. Determinations of recurrence or growth of the residual tumor tissue during the follow-up period were based on neuroradiological criteria.

RESULTS

Residual tumor after surgery was detected in 173 patients (36.4%). Multivariate analysis showed that invasion of the cavernous sinus, maximum tumor diameter, and absence of tumor apoplexy were associated with an unfavorable surgical outcome. At least 2 sets of follow-up neuroimaging studies were obtained in 436 patients (median follow-up 53 months). Tumors recurred in 83 patients (19.0%). When tumor removal appeared complete, younger age at surgery was associated with a risk of tumor recurrence. In patients with incomplete tumor removal, adjunctive postoperative radiotherapy had a marked protective effect against growth of residual tumor.

CONCLUSIONS

Complete surgical removal of NFPAs can be safely achieved in > 50% of cases. Visual symptoms and, less frequently, pituitary function may improve after surgery. However, tumor can recur in patients after apparently complete surgical removal. In patients with incomplete tumor removal, radiation therapy is the most effective adjuvant therapy for preventing residual tumor growth.

In vivo time-lapse imaging delineates the zebrafish pituitary proopiomelanocortin lineage boundary regulated by FGF3 signal

The anterior pituitary gland (adenohypophysis) comprises anterior and intermediate lobes (the pars distalis and pars intermedia) arising from placodal ectoderm at the anterior neural ridge. Signaling molecules including SHH, FGF, WNT, BMP and Notch are involved in regulating primordial pituitary proliferation and lineage determination. However, morphogenic events and molecular mechanisms governing anterior and intermediate lobe specification are not clear. Pituitary expression of proopiomelanocortin (POMC), the common precursor for adrenocorticotropin (ACTH) of pars distalis corticotropes and alpha-melanocyte-stimulating hormone (alpha-MSH) of pars intermedia melanotropes, provides a unique marker for anterior and intermediate lobe morphogenesis. We performed time-lapse confocal microscopy lineage tracing in live zebrafish embryos expressing GFP driven by the pomc promoter and show distinct migration pathways of POMC cells destined to the anterior and intermediate lobes. Using morpholino oligonucleotides, we show that hypomorphic FGF3 down-regulation induces specific defects of pars intermedia POMC cells while pomc, growth hormone and prolactin expression remain intact in the pars distalis. This lineage-specific process is independent of the FGF3 effect on early pituitary specifying transcription factors as indicated by normal Lim3 and Pit1 expression in hypomorphic FGF3 morphants. These findings suggest that the FGF3 signal, in addition to its previously described role of regulating progenitor proliferation and survival, delineates the melanotrope and corticotrope lineage boundary, contributing to establishment of the pituitary pars distalis and pars intermedia.

Matrix metalloproteinase-9, a potential biological marker in invasive pituitary adenomas

OBJECT

We analyzed MMP-9 expression using mRNA and protein level determinations and explored the possibility that matrix metalloproteinase-9 (MMP-9) is a potential biological marker of pituitary adenoma invasiveness and whether MMP-9 could be used to discriminate the extent of invasiveness among different hormonal subtypes, tumor sizes, growth characteristics, and primary versus recurrent tumors.

MATERIALS AND METHODS

73 pituitary tumor specimens were snap frozen in liquid nitrogen immediately after surgical resection. RNA and protein were extracted. MMP-9 mRNA transcripts were analyzed by quantitative RT-PCR. MMP-9 protein activity was analyzed by gelatin zymography and validated by western blot analysis. Immunohistochemistry was performed to identify the presence and localization of MMP-9 in pituitary adenomas. Statistical differences between results were determined using Student's t-test or one way ANOVA.

RESULTS

Comparing different hormonal subtypes of noninvasive and invasive pituitary tumors, MMP-9 mRNA expression was significantly increased in the majority of invasive adenomas. Considering the protein levels, our data also showed a significant increase in MMP-9 activity in the majority of invasive adenomas and these differences were confirmed by western blot analysis and immunohistochemistry. In addition, consistent differences in MMP-9 expression levels were found according to tumor subtype, tumor size, tumor extension and primary versus redo-surgery.

CONCLUSIONS

MMP-9 expression can consistently distinguish invasive pituitary tumors from noninvasive pituitary tumors and would reflect the extent of invasiveness in pituitary tumors according to tumor subtype, size, tumor extension, primary and redo surgery, even at early stages of invasiveness. MMP-9 may be considered a potential biomarker to determine and predict the invasive nature of pituitary tumors.

Defective expression of prohormone convertase 1/3 in silent corticotroph adenoma

Silent corticotroph adenoma (SCA) is defined as an ACTH-producing pituitary tumor not associated with clinical and endocrine feartures of Cushing's syndrome, but its underlying molecular mechanism(s) remains unknown thus far. We tested the hypothesis that reduced expression of prohormone convertase (PC) 1/3 responsible for proteolytic processing of proopiomelanocortin (POMC) in SCA may lead to production of unprocessed, biologically inactive POMC and/or precursor of ACTH. Among 30 non-functioning pituitary macroadenomas (NFA) examined, we found 6 SCAs by immunohistochemical study using anti-ACTH antibody. Preoperative endocrine and diagnostic image tests did not reveal any differences between SCA and the remaining NFA except for the higher recurrence rate of SCA. While steady-state PC1/3 mRNA levels determined by RT-PCR were almost comparable between SCAs and NFAs, immunohistochemical study showed negative immunostaining for PC1/3 in all 6 SCAs. Our data suggest that defective PC1/3 expression may lead to preferential production of unprocessed, biologically inactive ACTH variants in SCA.

Pituitary carcinoma: a review of the literature

Pituitary carcinomas, defined as distant metastases of a pituitary neoplasm, are rare; fewer than 140 reports exist in the English literature. The initial presenting pituitary tumor is usually a secreting, invasive macroadenoma, with adrenocorticotropic hormone (ACTH)--and prolactin (PRL)--secreting tumors being the most common. The latency period between the diagnosis of a pituitary tumor and the diagnosis of a pituitary carcinoma is 9.5 years for ACTH-producing lesions and 4.7 years for PRL-secreting tumors. Survival after documentation of metastatic disease is poor; 66% of patients die within 1 year. Treatment options include additional surgery, radiotherapy, and chemotherapy, all of which are associated with poor results. Future studies will focus on identifying those invasive pituitary tumors most likely to metastasize and treating them aggressively before they progress to pituitary carcinomas.

Crooke's cell adenoma of the pituitary: an aggressive variant of corticotroph adenoma

Cushing's disease is caused by functional corticotroph adenomas of the pituitary, mostly noninvasive microadenomas. Classic Crooke's cells are nonneoplastic corticotrophs with cytoplasmic accumulation of cytokeratin filaments in response to glucocorticoid excess. Corticotroph adenomas exhibiting Crooke's change are rare and incompletely understood. We intend to define more clearly the clinicopathological features of Crooke's cell adenomas (CCA). Thirty-six CCAs were retrieved from the files of Mayo Clinic and from our (B.W.S., K.K.) consultation files. The number of informative cases varied for different criteria. Clinical follow-up was obtained in 31 cases. The 27 females and 9 males were 18 to 81 years of age (mean 46 years). At presentation, Cushing's disease was evident in 22/34 (65%); 81% were macroadenomas and 72% were invasive. All were initially treated by transsphenoidal resection. Twenty-five patients were followed for more than 1 year (mean 6.7 years). Of these, 15 (60%) developed recurrent tumor, and 6 (24%) had multiple recurrences. Lastly, 3 of these 25 patients (12%) died of tumor: 1 after multiple local recurrences and 2 from pituitary carcinoma. Compared with typical corticotroph adenomas, CCAs are aggressive. Most are functional adenomas occurring in middle-aged women and are invasive macroadenomas prone to recurrence. Morbidity and mortality rates are substantial. CCAs represent a distinct entity that should be separated from corticotroph adenomas without Crooke's hyaline change.

Best Practice No 172: pituitary gland pathology

This article reviews published evidence on the diagnosis and classification of pituitary gland tumours and the relevance of histological and genetic features to prognosis. Much of the literature is devoted to the histological, ultrastructural, and immunocytochemical classification of pituitary adenomas (extensively supported by multicentre studies), with little consensus on the identification of prognostic features in adenomas, particularly in relation to invasion. There is a lack of correspondence between clinical and pathological criteria to identify and classify invasion, and a need to reassess the nomenclature and diagnostic criteria for invasive adenomas and carcinomas. Recent cytogenetic, genetic, and molecular biological studies have identified no consistent abnormalities in relation to pituitary tumour progression, although many genes are likely to be involved. In light of these uncertainties, an approach to the diagnosis and classification of pituitary adenomas is suggested, based on robust criteria from earlier studies and incorporating provisional data that require reassessment in large prospective studies with an adequate clinicopathological database.

Molecular defects in the pathogenesis of pituitary tumours

The majority of pituitary adenomas are trophically stable and change relatively little in size over many years. A comparatively small proportion behave more aggressively and come to clinical attention through inappropriate hormone secretion or adverse effects on surrounding structures. True malignant behaviour with metastatic spread is very atypical. Pituitary adenomas that come to surgery are predominantly monoclonal in origin and roughly half are aneuploid, indicating either ongoing genetic instability or transition through a period of genetic instability at some time during their development. Few are associated with the classical mechanisms of tumour formation but it is generally believed that the majority harbour quantitative if not qualitative differences in molecular composition compared to the normal pituitary. Despite their prevalence and the ready availability of biopsy material, at the present time, the precise molecular pathogenesis of the majority of pituitary adenomas remains unclear. This review summarizes current thinking.

Silent corticotroph carcinoma of the adenohypophysis: a report of five cases

We report five silent corticotroph carcinomas of the pituitary gland. They represent 0.05% of adenohypophyseal tumors surgically treated at Mayo Clinic during a 20-year period and about 5% of all reported pituitary carcinomas. The patients (three females and two males), ranging in age from 26 to 58 years (mean 39 years, median 35 years) presented with symptoms of mass effect; none had Cushing's disease. All tumors were initially invasive macroadenomas, recurred locally, and metastasized, three outside the central nervous system. The follow-up period ranged from 2 to 23 years (mean 10.6 years). All patients died, four of disseminated tumor and one of myocardial infarction. Histologically, three of the primary lesions were indistinguishable from an ordinary benign adenoma. Two were initially diagnosed as atypical adenomas as they featured nuclear pleomorphism, prominent nucleoli, mitotic activity, high MIB-1 labeling indices, and p53 overexpression. For the purpose of comparison, 17 silent corticotroph adenomas were also investigated. In addition, the clinicopathologic features of the silent carcinomas were compared with those of a meta-analysis of published Cushing's disease-associated pituitary carcinomas. The silent adrenocorticotropin carcinomas showed a propensity for extraneural dissemination and an outcome similar to those of the Cushing's disease-associated carcinomas. The two patients with initial atypical tumors died with metastases outside the central nervous system at 2 and 4 years, whereas the three patients with tumors lacking atypia died 16, 18, and 23 years after initial sellar surgery.

Comparison of ACTH secretion in Cushing's adenoma and clinically silent corticotroph adenoma by cell immunoblot assay

Immunocytochemical staining and cell immunoblot assay (CIBA) were performed in adenoma tissue from five patients with Cushing's disease and three patients with clinically silent corticotroph adenomas. All five patients with Cushing's disease showed hypersecretion of ACTH (130, 190, 331, 120, and 130 pg/ml), high levels of serum cortisol (26.6-44.0 micrograms/dl), and symptoms of Cushing's disease. All three patients with silent corticotroph adenoma showed hypersecretion of ACTH (110, 140, and 160 pg/ml) and normal levels of serum cortisol (11.4-26.8 micrograms/dl). The size of the pituitary adenoma on magnetic resonance imaging was smaller in patients with Cushing's disease (mean 8.2 mm) than in patients with silent corticotroph adenoma (mean 26.7 mm) (p = 0.001). Transsphenoidal surgery was performed to totally resect the adenoma tissue. Immunostaining for ACTH showed diffuse ACTH-immunopositive cells in all eight adenomas. CIBA technique showed a good correlation between percentage of ACTH-immunopositive cells and level of plasma ACTH in patients with Cushing's disease but no correlation between the two parameters in patients with silent corticotroph adenoma. The percentage of ACTH-secreting cells and the amount of hormone secreted by a single cell are too low in silent corticotroph adenomas to cause an increase in plasma ACTH level corresponding to the large tumor size.

Significance of absent prohormone convertase 1/3 in inducing clinically silent corticotroph pituitary adenoma of subtype I--immunohistochemical study

Biologically inactive ACTH-producing pituitary adenoma is known as clinically silent corticotroph adenoma. To search for the mechanism causing clinically silent corticotroph adenoma, we immunohistochemically examined the expression of prohormone convertase 1/3 (PC1/3) in this type of adenoma and compared our results with those obtained for Cushing's disease. All of the Cushing's disease specimens exhibited strongly positive PC1/3 exhibition. On the contrary, the expression of PC1/3 was very weak in the clinically silent corticotroph adenoma specimens. The absence of PC1/3 in clinically silent corticotroph adenoma indicates that silent corticotroph adenomas arise in a different cell type sharing the prohormone pro-opiomelanocortin (POMC), but processing it differently, accounting for the lack of clinical symptoms due to ACTH excess.

Crooke's hyalinization in silent corticotroph adenoma: report of two cases

Corticotroph adenomas rarely show Crooke's hyaline change in neoplastic cells, a feature similar to that of normal corticotroph cells exposed to excess cortisol. Crooke's cell adenomas are usually associated with Cushing's disease. Nonfunctioning examples are uncommon. We report two clinically silent corticotroph adenomas featuring extensive Crooke's hyalinization in neoplastic cells. The two patients were 49 and 59 yr of age and neither had Cushing's disease. Serum and urinary cortisol were normal. One patient had elevated serum adrenocorticotropic hormone. In our experience, the two patients accounted for 0.4% of pituitary adenomas operated on from January 1992 to December 2001 and 3.5% of all corticotroph adenomas. The two lesions had features of the subtype 1 silent corticotroph adenoma. Cytogenetic analysis performed on one lesion showed a normal karyotype (46;XY). Hyalinization in clinically silent Crooke's cell adenoma indicates that hyaline changes do not always relate to excess cortisol. It is known that neoplastic Crooke's cells show immunoreactivity for glucocorticoid receptors stronger than nontumorous Crooke's corticotrophs. This fact suggests that receptor overexpression or lack of receptor downregulation may result in hypersensitivity of neoplastic Crooke's cells to physiologic cortisol plasma levels.

Classification of pituitary adenomas

This brief review summarizes various schemes which were introduced to classify pituitary tumors of adenohypophysial origin. Many different classifications were proposed. Pathologists prefer classifications based on the morphologic features of tumor cells. The gold standard is the light microscopic study of hematoxylin-eosin stained sections of formalin fixed and paraffin-embedded tissues. For correlation between hormone production, secretory activity and cytogenesis, immunohistochemical and transmission electron microscopic investigation is needed. We are convinced that in the future, molecular and genetic techniques will also be applied. We present here our five-tier scheme for classification of pituitary tumors which was accepted by the 'World Health Organization International Histological Classification of Tumours'. This classification takes into consideration the clinical and laboratory findings, imaging results, histologic, immunocytochemical and ultrastructural features of tumor cells. Despite several recent attempts to assess the growth rate, aggressiveness and invasiveness of pituitary tumors, more work is required to draw conclusions on their prognosis.