Clinically silent somatotroph adenomas are common

Suspected silent pituitary somatotroph neuroendocrine tumor associated with acromegaly-like bone disorders: a case report

BACKGROUND

Growth hormone (GH) positive pituitary neuroendocrine tumors do not always cause acromegaly. Approximately one-third of GH-positive pituitary tumors are classified as non-functioning pituitary tumors in clinical practice. They typically have GH and serum insulin-like growth factor 1 (IGF-1) levels in the reference range and no acromegaly-like symptoms. However, normal hormone levels might not exclude the underlying hypersecretion of GH. This is a rare and paradoxical case of pituitary tumor causing acromegaly-associated symptoms despite normal GH and IGF-1 levels.

CASE PRESENTATION

We report a case of a 35-year-old woman with suspicious acromegaly-associated presentations, including facial changes, headache, oligomenorrhea, and new-onset diabetes mellitus and dyslipidemia. Imaging found a 19 × 12 × 8 mm pituitary tumor, but her serum IGF-1 was within the reference, and nadir GH was 0.7ng/ml after glucose load at diagnosis. A thickened skull base, increased uptake in cranial bones in bone scan, and elevated bone turnover markers indicated abnormal bone metabolism. We considered the pituitary tumor, possibly a rare subtype in subtle or clinically silent GH pituitary tumor, likely contributed to her discomforts. After the transsphenoidal surgery, the IGF-1 and nadir GH decreased immediately. A GH and prolactin-positive pituitary neuroendocrine tumor was confirmed in the histopathologic study. No tumor remnant was observed three months after the operation, and her discomforts, glucose, and bone metabolism were partially relieved.

CONCLUSIONS

GH-positive pituitary neuroendocrine tumors with hormonal tests that do not meet the diagnostic criteria for acromegaly may also cause GH hypersecretion presentations. Patients with pituitary tumors and suspicious acromegaly symptoms may require more proactive treatment than non-functioning tumors of similar size and invasiveness.

The clinical presentation of PIT1 positive pituitary neuroendocrine tumor immunonegative for growth hormone, prolactin, and thyroid stimulating hormone with analysis of clinical and immunostaining dissociation

BACKGROUND

PIT1 is a pituitary transcription factor that is associated with either growth hormone (GH), prolactin (PRL), or thyroid-stimulating hormone (TSH) production. However, PIT1-positive pituitary neuroendocrine tumors (PitNETs) are occasionally immunonegative for GH, PRL, and TSH. This paper describes the clinical presentation of PIT1 positive however immunonegative PitNETs.

METHODS

We conducted a retrospective analysis, identifying 228 PIT1-positive PitNET patients between 2017 and 2022. Out of these, ten (4%) tested negative for GH, PRL, and TSH. Functioning PitNETs were defined as those causing hormonal excess symptoms or hormonal overproduction.

RESULTS

As for 10 patients immunonegative for all three hormones however PIT1-positive, the mean ( ± standard deviation) age was 46 ± 13 years with 70% women. Six patients exhibited signs of excess GH or PRL, and three had visual problems. Additionally, one patient had secondary hypothyroidism and adrenal insufficiency resulting from the mass effect. All tumors were macroadenoma, with a median volume of 2.1 cm3 (range, 0.8-17.5 cm3). Gross total resection was attained in six patients by trans-sphenoidal surgery. Postoperatively, eight patients experienced clinical improvement: three in vision, two in amenorrhea, two in headache, and one in acromegaly symptoms. Biochemical improvement was observed in six patients, with all experiencing remission in hormonal excess and one showing improvement in secondary hypothyroidism. Stereotactic radiosurgery was performed in three patients.

CONCLUSIONS

Patients with functioning PitNETs may exhibit PIT1 staining without GH, PRL, or TSH staining. Hormonally active tumors exist in this patient population; therefore, close endocrine follow-up is necessary despite the lack of staining for GH, PRL, and TSH.

Acromegaly with initial negative oral glucose tolerance test: a case report

BACKGROUND

Acromegaly can be diagnosed by a growth hormone value ≥ 1 µg/L following an oral glucose tolerance test. However, normal growth hormone suppression following oral glucose tolerance test may not exclude acromegaly.

CASE PRESENTATION

We present a case of a 55-year-old Chinese man with pituitary macroadenoma incidentally noted after a traffic accident. He reported feet enlargement in the past few years. At the beginning, elevated insulin-like growth factor-1 was noted with growth hormone value < 1 µg/L after oral glucose tolerance test. Fracture-related high insulin-like growth factor-1 was suspected. Insulin-like growth factor-1 decreased gradually but was still above the upper limit of normal . However, he suffered from dizziness 1 year later and insulin-like growth factor-1 increased again. Besides, secondary hypocortisolism developed. The size of the pituitary macroadenoma was stationary. Follow-up oral glucose tolerance test showed a growth hormone value > 1 µg/L. Endoscopic endonasal approach to the remove pituitary macroadenoma was performed subsequently. After the resection of the pituitary macroadenoma, pathology showed positive staining of growth hormone and prolactin. Insulin-like growth factor-1 normalized as well.

CONCLUSIONS

Suppressed growth hormone after oral glucose tolerance test cannot exclude acromegaly, and some patients may have only mild or no clinical presentation of acromegaly. Patients with pituitary microadenoma or macroadenoma and elevated insulin-like growth factor-1 should be closely monitored for signs/symptoms of acromegaly and hypopituitarism.

Subclinical acromegaly: to treat or not to treat?

Patients with acromegaly usually present with the classical signs of acromegaly, whereas patients without the specific signs or symptoms are rarely diagnosed. This unique entity can be named "subclinical acromegaly". This was a retrospective study. Our study group consisted of 6 patients (4 females) with incidentally diagnosed acromegaly, most following head MRI for unrelated reasons and without the specific signs of acromegaly. Mean age at diagnosis was 48.8 ± 19.2 years. Baseline IGF-1 ranged between 1.3-2.0 × upper limit of normal (ULN). MRI depicted a pituitary microadenoma in 5 patients, and one patient presented with a 12 mm intra-sellar macroadenoma. Mean calculated SAGIT clinical score was 4.8. Three patients underwent trans-sphenoidal resection; two achieved hormonal remission and one improved but did not normalize IGF-1 following surgery. Four patients (including one following surgery) were given somatostatin analogs, and three normalized IGF-1. Several patients improved clinically following treatment, reporting improvement in snoring, hypertension, or weight loss, and pituitary adenoma decreased in size in 2 patients that responded to medical treatment. We report a series of 6 patients with very mild and subclinical acromegaly. It is uncertain whether all such patients will gain clinical benefit from treatment, but most experienced clinical improvement due to treatment.

Aggressive nonfunctioning pituitary neuroendocrine tumors

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

Silent Corticotroph and Somatotroph Double Pituitary Adenoma: A Case Report and Review of Literature

Clinically silent double pituitary adenomas consisting of corticotroph and somatotroph cells are an exceedingly rare clinical finding. In this report, we present the case of a 28-year-old man with a 1-year history of recurrent headaches. Imaging revealed a 2.1 (anterior-posterior) × 2.2 (transverse) × 1.3 (craniocaudal) cm pituitary adenoma invading into the left cavernous sinus and encasing the left internal carotid artery. Endoscopic transnasal resection was performed without complications. Immunohistochemical staining revealed a double adenoma consisting of distinct sparsely granulated somatotroph and densely granulated corticotroph cells that were positive for growth hormone and adrenocorticotropic hormone, respectively. K _i -67 index labeling revealed a level of 6% within the corticotroph adenoma. No increase in serum growth hormone or adrenocorticotropic hormone was found, indicating a clinically silent double adenoma. While transsphenoidal surgery remains a first-line approach for silent adenomas presenting with mass effects, increased rates of proliferative markers, such as the K _i -67 index, provide useful insight into the clinical course of such tumors. Determining the K _i -67 index of silent pituitary adenomas could be valuable in predicting recurrence after initial surgical resection and identifying tumors that are at an increased risk of needing additional therapeutic interventions or more frequent surveillance imaging.

Metachronous Double Pituitary Adenoma with Altered Transcriptional Factor Profile: A Case Report and Literature Review

Double pituitary adenomas (DPAs), especially metachronous DPAs, are extremely rare and there has been no report about DPAs with altered transcriptional factors. We describe the case of a 25-year-old man who presented with acromegaly 7 years after surgery for a non-functioning pituitary adenoma (NFPA). Before the initial surgery, endocrine evaluation confirmed NFPA or silent somatotroph pituitary adenoma (SPA) because of normal serum levels of insulin-like growth factor-1 (IGF-1) and insufficient suppression of growth hormone (GH) levels in the oral glucose tolerance test (OGTT). Immunohistochemistry of resected tissue obtained from gross total resection (GTR) with transsphenoidal surgery (TSS) was negative for follicle-stimulating hormone, luteinizing hormone, GH, and Pit-1 but positive for GATA3, which confirmed the gonadotroph pituitary adenoma (GPA) diagnosis. Seven years later, follow-up brain MRI revealed a 13.3 × 5.6 × 4.7 mm tumor within the sellar turcica. The endocrine evaluation confirmed acromegaly because of high serum levels of IGF-1 and insufficient suppression of GH levels upon OGTT. GTR with TSS was again performed, and immunohistochemistry was negative for GATA3 but positive for GH and Pit-1. Surprisingly, he showed altered transcription factor expressions between initial and recurrent surgery. Based on the overall clinical course and hormonal secretion findings, we speculated metachronous development of a DPA, i.e., SPA followed by GPA, wherein a few remaining cells of the SPA might have regrown after the initial surgery. We conducted a literature review of cases that documented altered hormone secretion at recurrence and emphasized the necessity of identifying a small adenoma when there is a discrepancy between pathological findings and hormone secretion tests.

Clinico-Radiological Features of Tumor-like Lesions of the Upper Limbs: don't worry about those lumps

Tumor-like lesions of the upper limb are more frequent than malignant neoplastic lesions and they represent a wide and heterogeneous group of disorders. The combination of clinical evaluation and imaging is the first pivotal step to attempt a distinction between benign and malignant masses, since there are important implications for further management, such as the requirement for conservative or interventional treatment. The classification of these pseudo tumoral lumps remains arbitrary and is still a matter of debate, currently based on a conjunct clinico-radiologic approach. In this article, we review various types of tumor-like lesions of the upper limb in terms of imaging approach and related clinic features, proponing a descriptive classification, useful in clinical practice to recognize these disorders, and to avoid unnecessary or potentially harmful procedures.

Guidelines in the management of CNS tumors

INTRODUCTION

Evidence-based, clinical practice guidelines in the management of central nervous system tumors (CNS) continue to be developed and updated through the work of the Joint Section on Tumors of the Congress of Neurological Surgeons (CNS) and the American Association of Neurological Surgeons (AANS).

METHODS

The guidelines are created using the most current and clinically relevant evidence using systematic methodologies, which classify available data and provide recommendations for clinical practice.

CONCLUSION

This update summarizes the Tumor Section Guidelines developed over the last five years for non-functioning pituitary adenomas, low grade gliomas, vestibular schwannomas, and metastatic brain tumors.

Toxicity Profiles of Fractionated Radiotherapy, Contemporary Stereotactic Radiosurgery, and Transsphenoidal Surgery in Nonfunctioning Pituitary Macroadenomas

Background: Here, we compared the toxicity profiles of contemporary stereotactic radiosurgery (SRS), modern fractionated radiotherapy (FRT), and transsphenoidal surgery used to treat nonfunctioning pituitary macroadenomas. Methods: We included the data of patients with nonfunctioning pituitary macroadenomas. To compare treatment outcomes, the patients were categorized groups 1 (those receiving modern FRT), 2 (those receiving contemporary SRS), and 3 (those receiving transsphenoidal surgery). The multivariable Cox proportional hazards regression analysis was performed to yielded adjusted hazard ratios (aHRs) and their 95% CIs for local recurrence in groups 2 and 3 compared with group 1. Results: We included the data of 248 patients with nonfunctioning pituitary macroadenomas. The analytical results revealed no significant differences in second primary brain or head and neck cancer, hypopituitarism, or optic nerve injury between the three cohorts. The multivariable Cox proportional hazards regression analysis revealed that compared with group 1, the aHRs (95% CIs) for stroke risk in groups 2 and 3 were 0.37 (0.14–0.99) and 0.51 (0.31–0.84), respectively. Conclusion: Contemporary SRS and transsphenoidal surgery for nonfunctioning pituitary macroadenoma treatment have equivalent toxicity profiles. However, modern FRT for nonfunctioning pituitary macroadenoma treatment might considerably increase stroke risk.

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.

Early surgical intervention for patients with possible clinically silent somatotroph adenoma: a case series

Introduction

Clinically silent somatotroph adenoma is characterized by elevated serum growth hormone but without the clinical symptoms of acromegaly, and it is considered rare. The natural history is not well understood, progress to symptomatic is uncertain, and treatment strategy has not been established.

Case presentation

The first patient was a 48-year-old-Asian woman who presented with serum growth hormone 6.99 ng/ml and insulin-like growth factor 1 of 476 ng/ml, but no characteristic features of acromegaly. Five years after initial diagnosis, she presented with acromegalic facial appearance. Transsphenoidal surgery achieved gross total removal and endocrinological remission. The second patient was a 40-year-old-Asian woman who presented with serum growth hormone 31.14 ng/ml and insulin-like growth factor 1 of 709.6 ng/ml, but no characteristic features of acromegaly. Three years after initial diagnosis, she presented with acromegalic facial appearance. Transsphenoidal surgery achieved gross total removal and endocrinological remission. The third patient was a 64-year-old-Asian woman who presented with serum growth hormone 6.0 ng/ml and insulin-like growth factor 1 of 341 ng/ml, but no characteristic features of acromegaly. Eight months after initial diagnosis, hand enlargement was detected. Transsphenoidal surgery achieved gross total removal and endocrinological remission.

Conclusion

Due to its potential for evolving to symptomatic disease, the risks of surgery and observation for patients with somatotroph adenoma should be carefully compared from the viewpoint of better health outcome.

[Morphofunctional features of non-functioning pituitary adenomas]

Non-functioning pituitary adenomas (NFPAs) account for about 30% of all pituitary tumors. NFPAs are characterized by the lack of secretory potential or its weak expression insufficient for determination of the blood level of adenohypophyseal tropic hormones and for development of a specific clinical picture. Morphologically, NFPAs are a heterogeneous group of tumors, the classification of which was previously based only on immunoreactivity for pituitary tropic hormones. The WHO revised its Classification of Tumors of Endocrine Organs (4th edition) in 2017. The main changes relate to adenohypophysial-cell lineage for the designation of adenomas into subtypes. The introduction of transcription factor antibodies has become a fundamentally new approach to the classification of NFPAs, which is necessary to recognize less differentiated tumor types. This paper provides information on the new histopathological classification of pituitary adenomas, on the theories of silent adenomas, and on the proliferative and prognostic markers of NFPAs.

Malignant transformation in non-functioning pituitary adenomas (pituitary carcinoma)

Non-functioning pituitary carcinomas (NFPC) are defined as tumours of adenophyseal origin with craniospinal or systemic dissemination, with the absence of a hormonal hypersecretion syndrome. These are a histologically heterogenous group of tumours, comprising gonadotroph, null cell, "silent" tumours of corticotroph, somatotroph or lactotroph cell lineages as well as plurihormonal Pit-1 tumours. NFPC are exceedingly rare, and hence few cases have been described. This review has identified 38 patients with NFPC reported in the literature. Recurrent invasive non-functioning pituitary adenomas (NFPA) were observed in a majority of patients. Various factors have been identified as markers of the potential for aggressive behaviour, including rapid tumour growth, growth after radiotherapy, gain or shift of hormone secretion and raised proliferative markers. Typically, there is a latency of several years from the original presentation with an NFPA to identification of metastases and only 5 cases reported with rapidly progressive malignant disease within 1 month of presentation. Therapeutic options include debulking surgery, radiation therapy and chemotherapy with temozolomide recommended as first line systemic treatment. Although long-term survivors are described, prognosis remains generally very poor (median survival 8 months). Improvements in molecular tumour profiling may assist in predicting tumour behaviour, guide therapeutic choices and identify novel therapies.

Silent somatotroph pituitary adenomas: an update

Silent growth hormone adenomas (SGHA) are a rare entity of non-functioning pituitary neuroendocrine tumors. Diagnosis is invariably made post-operatively of a tumor immunopositive for GH (and Pit-1 in selected cases) but without clinical acromegaly. Mainly young females are affected, and tumors are often uncovered by investigation for headaches or oligoamenorrhea. Integration of clinical, pathological and biochemical data is required for proper diagnosis. Beside normal IGF-1 levels, a third of SGHAs displays elevated GH levels and some will eventually progress to acromegaly. Almost two-thirds will be mixed GH-prolactin tumors and sparsely-granulated monohormonal GH tumors seems the more aggressive subtype. Recurrence and need for radiation is higher than other non-functioning tumors so close follow-up is warranted.

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.

Clinical profile of silent growth hormone pituitary adenomas; higher recurrence rate compared to silent gonadotroph pituitary tumors, a large single center experience

PURPOSE

Study and comparison of characteristics of silent growth hormone adenomas (SGHA), silent corticotroph adenomas (SCA), and silent gonadotroph adenomas (SGA) in a single institution cohort of surgically treated pituitary adenomas.

METHODS

Retrospective analysis of SGHA surgically resected over 10 years: SGHA was defined as no clinical or biochemical evidence of acromegaly and positive GH immunostaining.

RESULTS

Of 814 pituitary surgeries; 2.1% (n = 17) were SGHA, 4.5% (n = 37) SCA, and 18.9% (n = 70/371; 2011-2016) SGA. Mean age at SGHA diagnosis was 43 years, with a large female predominance (82%). Mean tumor size and cavernous/sphenoid sinus invasiveness for SGHA, SCA, and SGA were 1.5 ± 1.0 cm and 25%, 2.5 ± 1.2 cm and 43%, 2.9 ± 2.0 cm and 41%, respectively (tumor size p = 0.009, SGHA vs. SGA, and invasion p; not-significant). During mean follow-up of 3.9 years, two patients (11%) developed elevated insulin-like growth factor-1 and five patients (29%) required a second surgery for tumor recurrence. Rate of surgical reintervention was similar to SCA (31%), but higher than SGA (10%) (p = 0.035, SGHA vs. SGA), and 18% underwent radiation therapy, similar to SCA (19%, p; not-significant) but higher than SGA (2.9%, p = 0.018).

CONCLUSION

This is the largest single center study characterizing SGHA behavior with SGA and SCA control groups in a cohort of surgically resected pituitary adenomas. SGHA present mostly in young females, and should be closely followed due to their higher likelihood of recurrence and potential of progression to clinical acromegaly. We propose that a complete hormonal staining panel be routinely performed for all pituitary adenomas.

Silent somatotroph tumour revisited from a study of 80 patients with and without acromegaly and a review of the literature

BACKGROUND

Silent somatotroph tumours are growth hormone (GH) immunoreactive (IR) pituitary tumours without clinical and biological signs of acromegaly. Their better characterisation is required to improve the diagnosis.

MATERIALS AND METHODS

Twenty-one silent somatotroph tumours were compared to 59 somatotroph tumours with acromegaly. Tumours in each group were classified into GH and plurihormonal (GH/prolactin (PRL)/±thyroid-stimulating hormone (TSH)) and into densely granulated (DG) and sparsely granulated (SG) types. The two groups were then compared with regards to proliferation (Ki-67, p53 indexes and mitotic count), differentiation (expression of somatostatin receptors SSTR_2A-SSTR₅ and transcription factor Pit-1) and secretory activity (% of GH- and PRL-IR cells).

RESULTS

The silent somatotroph tumours represented 2% of all tested pituitary tumours combined. They were more frequent in women than in men (P = 0.002), more frequently plurihormonal and SG (P < 0.01), with a lower percentage of GH-IR cells (P < 0.0001) compared to those with acromegaly. They all expressed SSTR_2A, SSTR₅ and Pit-1. The plurihormonal (GH/PRL/±TSH) tumours were mostly observed in women (sex ratio: 3/1) and in patients who were generally younger than those with acromegaly (P < 0.001). They were larger (P < 0.001) with a higher Ki-67 index (P = 0.007).

CONCLUSIONS

The silent somatotroph tumours are not uncommon. Their pathological diagnosis requires the immunodetection of GH and Pit-1. They are more frequently plurihormonal and more proliferative than those with acromegaly. A low secretory activity of these tumours might explain the normal plasma values for GH and insulin-like growth factor 1 (IGF1) and the absence of clinical signs of acromegaly.

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.

"Micromegaly": an update on the prevalence of acromegaly with apparently normal GH secretion in the modern era

PURPOSE

Approximately 25 % of cases of clinically active acromegaly cases treated in our academic center between 1996 and 2000, were diagnosed in patients who had elevated plasma IGF-1 levels, but apparently "normal" 24-h mean plasma GH levels. The current study served to update the data for patients with acromegaly referred to our facility, after increasing awareness of this "normal" GH subpopulation throughout the medical community.

METHODS

A retrospective chart review was conducted on 157 patients with acromegaly who underwent resection of a confirmed somatotroph pituitary adenoma at the University of Michigan Health System between the dates of 1 Jan 2001 to 23 Sept 2015.

RESULTS

Overall prevalence of acromegalic patients with "normal" GH levels, defined as GH <4.7 ng/mL, was 31 %. Over time, the percentage of patients with "normal" GH at diagnosis did not decline: 26 % from 2001 to 2005, 19 % from 2006 to 2010, and 47 % from 2011 to 2015. Mean pituitary tumor size was 1.8 ± 0.1 cm for the group with elevated GH, and 1.2 ± 0.1 cm for the group with "normal" GH (p < 0.001). Percent microadenomas was higher in a group with "normal" GH as compared to those with elevated GH (48 vs. 12 %, p < 0.001), and tumors >2 cm in the maximal diameter were encountered more frequently in the group with elevated GH (43 vs. 14 %, p < 0.001).

CONCLUSIONS

Our data show that a substantial percentage of patients with clinical acromegaly have "normal" GH, and therefore strengthens the growing body of evidence which supports the leading role of IGF-1 levels in diagnostic evaluation. At the present time, questions about the natural course of "micromegaly" and treatment benefits compared to the subpopulation with elevated GH levels remain unanswered, but research continues to build on our understanding of the heterogeneous population of individuals.

Long-term results of hypofractionated stereotactic radiotherapy with CyberKnife for growth hormone-secreting pituitary adenoma: evaluation by the Cortina consensus

The aim of the present study was to evaluate the safety and feasibility of hypofractionated stereotactic radiotherapy (SRT) with CyberKnife for growth hormone-secreting pituitary adenoma (GH-PA). Fifty-two patients with GH-PA were treated with hypofractionated SRT between September 2001 and October 2012. Eight patients had clinically silent GH-PA and 44 were symptomatic. Only 1 patient was inoperable. The other patients had recurrent or postoperative residual tumors on MRI. All patients had received pharmacotherapy prior to SRT with a somatostatin analog, dopamine agonist, and/or GH receptor antagonist. The marginal doses were 17.4-26.8 Gy for the 3-fraction schedule and 20.0-32.0 Gy for the 5-fraction schedule. Endocrinological remission was assessed by the Cortina consensus criteria 2010 (random GH <1 ng/ml or nadir GH after an oral glucose tolerance test <0.4 ng/ml and normalization of age- and sex-adjusted insulin-like growth factor-1). The median follow-up period was 60 months (range 27-137). The 5-year overall survival, local control, and disease-free survival rates were 100, 100, and 96 %, respectively. Nine patients (5 clinically silent and 4 symptomatic patients) satisfied the Cortina criteria without receiving further pharmacotherapy, whereas the remaining 43 patients did not. No post-SRT grade 2 or higher visual disorder occurred. Symptomatic post-SRT hypopituitarism was observed in 1 patient. CyberKnife hypofractionated SRT is safe and effective when judged by imaging findings for GH-PA. However, it may be difficult to satisfy the Cortina consensus criteria in most symptomatic patients with SRT alone. Further investigations of optimal treatments are warranted.

Treatment of invasive silent somatotroph pituitary adenoma with temozolomide. Report of a case and review of the literature

Improved imaging techniques have contributed to increased diagnosis of pituitary tumors. These tumor types can be microadenomas or macroadenomas and can either be functional or non-functional. Atypical or aggressive pituitary adenomas are tumors that rapidly increase in size and may invade into the suprasellar or parasellar regions. They are characterized by a Ki-67 nuclear labeling index greater than 10 %. Management of these tumors is difficult, and many recur after surgery. Temozolomide, a second generation alkylating agent, has been showing promising results in the treatment of these tumors. The patient was a 39-year-old male diagnosed with an invasive silent somatotroph pituitary macroadenoma treated with temozolomide after surgery. We present the case along with the review of the literature of the therapeutic effects of temozolomide in somatotroph macroadenomas.

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.

A prognostic clinicopathologic classification of pituitary endocrine tumors

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

Temozolomide Therapy for Aggressive Pituitary Tumors: Results in a Small Series of Patients from Argentina

We evaluated results of temozolomide (TMZ) therapy in six patients, aged 34-78 years, presenting aggressive pituitary tumors. In all the patients tested O(6)-methylguanine-DNA methyltransferase (MGMT) immunoexpression in surgical specimens was absent. Patients received temozolomide 140-320 mg/day for 5 days monthly for at least 3 months. In two patients minimum time for evaluation could not be reached because of death in a 76-year-old man with a malignant prolactinoma and of severe neutro-thrombopenia in a 47-year-old woman with nonfunctioning pituitary adenoma. In two patients (a 34-year-old acromegalic woman and a 39-year-old woman with Nelson's syndrome) no response was observed after 4 and 6 months, respectively, and the treatment was stopped. Conversely, two 52- and 42-year-old women with Cushing's disease had long-term total clinical and radiological remissions which persisted after stopping temozolomide. We conclude that TMZ therapy may be of variable efficacy depending on-until now-incompletely understood factors. Cooperative work on a greater number of cases of aggressive pituitary tumors should be crucial to establish the indications, doses, and duration of temozolomide administration.

Change in the immunophenotype of a somatotroph adenoma resulting in gigantism

BACKGROUND

Examining the pathologic progression of a pituitary adenoma from the point of a prepubescent child to an adult with gigantism affords us an opportunity to consider why patients may develop secretory or functioning tumors and raises questions about whether therapeutic interventions and surveillance strategies could be made to avoid irreversible phenotypic changes.

CASE DESCRIPTION

A patient underwent a sublabial transsphenoidal resection for a clinically non-functioning macroadenoma in 1999. He underwent radiation treatment and was transiently given growth hormone (GH) supplementation as an adolescent. His growth rapidly traversed several percentiles and he was found to have elevated GH levels. The patient became symptomatic and was taken for a second neurosurgical procedure. Pathology and immunohistochemical staining demonstrated a significantly higher proportion of somatotroph cells and dense granularity; he was diagnosed with a functional somatotroph adenoma.

CONCLUSIONS

While it is likely that the described observations reflect the manifestations of a functional somatotroph adenoma in development, it is possible that pubertal growth, GH supplementation, its removal, or radiation therapy contributed to the described endocrine and pathologic changes.

Absence of immunostaining for growth hormone in a subset of patients with acromegaly

The presence of growth hormone (GH) immunostaining in patients who lack the biochemical and clinical features of acromegaly has been described. In contrast, there is little information on the absence of GH immunostaining in patients with acromegaly. We describe five patients with acromegaly with no intratumoral immunostaining for GH. We reviewed all patients undergoing surgery for acromegaly. Out of 136 patients treated surgically in a 10 year period, five (3.7%) were found to have no GH immunostaining on repetitive testing at pathological examination. Their pathology slides were re-examined by an experienced neuropathologist, along with twenty nonfunctional pituitary tumors and ten GH-positive adenomas as negative and positive controls, respectively. All patients had clinical features consistent with acromegaly and elevated baseline insulin-like growth factor-1 (IGF-1) and GH. All patients had no immunostaining for GH on multiple inspections. Of twenty patients with nonfunctional tumors, two had ≤25% staining for GH in a scattered and non-coherent pattern and the rest were negative. In all ten positive control patients >25% of the tumor cells stained diffusely for GH. All five patients achieved biochemical remission at 1.4-8 years post-op using a combination of primary surgery alone (n = 1), repeat surgery (n = 1), radiotherapy (n = 3) and/or medical therapy (n = 2). GH immunostaining of an adenoma may not be sufficient to confirm the diagnosis of acromegaly. All patients in our small series achieved remission by multimodality therapies. Further studies are needed to evaluate the significance of our observation and whether this subset of patients follows a distinct long term clinical course.

Pathophysiology and treatment of subclinical Cushing's disease and pituitary silent corticotroph adenomas [Review]

Pituitary adrenocorticotropic hormone (ACTH)-secreting tumor presents with a variety of clinical features. We outlined the features of ACTH release and characteristics of corticotroph adenoma cells. We especially focused on the corticotroph adenomas in patients with no clinical features of Cushing's disease. Subclinical Cushing's disease is defined by ACTH-induced mild hypercortisolism without typical features of Cushing's disease. Silent corticotroph adenomas (SCAs) are defined by normal cortisol secretion and ACTH-immunopositive staining without autonomous ACTH secretion. Clinicians who are not well-informed about the disease may sometimes confuse SCAs (because of their clinically silent nature) with "subclinical Cushing's disease". The recent criteria for diagnosing subclinical Cushing's disease in Japan are presented. Cortisol measurement was recently standardized in Japan, so plasma cortisol cutoff level should be reconsidered for the diagnosis. In patients with uncontrolled diabetes and hypertension despite appropriate treatment, subclinical Cushing's disease may be efficiently detected. Subclinical Cushing's disease may be associated with metabolic change. In subclinical Cushing's disease, mild hypercortisolism due to autonomous secretion of ACTH contributes to metabolic change and treatment of subclinical hypercortisolism can reverse this change.

Pituitary incidentalomas: application of an evidence-based approach at the individual patient and population levels

With the widespread use of imaging techniques, incidental discovery of clinically unsuspected pituitary adenomas is increasing in frequency and will increase further. The Endocrine Society Task Force on Pituitary Incidentalomas has developed practice guidelines which reflect the best available evidence combined with the opinions of experts in pituitary diseases. For incidental macroadenomas, evidence supporting comprehensive evaluation (for hyperfunction, hypopituitarism and anatomy) and management (whether surgical or careful follow-up) is strong. By contrast, evidence supporting approaches to microadenomas without clinical suggestion of hormonal hypersecretion are relatively weak and practice varies. Developing more evidence will require approaches other than randomized controlled trials, such as comparative effectiveness studies. Incidentalomas represent part of a larger societal issue, that being overdiagnosis and its consequences.

Aggressive silent GH pituitary tumor resistant to multiple treatments, including temozolomide

Temozolomide (TMZ) has been proposed as a therapeutic option in aggressive pituitary tumors. Among the published cases, GH expressing tumors were rare. We describe a patient with initially benign silent GH adenoma that transformed into an aggressive GH secreting tumor resistant to usual therapy. MGMT expression was high and the MGMT promoter was unmethylated. Before this aggressive course, patient received three cycles of TMZ; no response was observed. Four cases of GH aggressive tumor treated by TMZ have been reported. Response to TMZ was observed in one of these four patients. Predictive factors of failure of TMZ remain unclear.

The changing face of acromegaly--advances in diagnosis and treatment

Acromegaly is a chronic disease characterized by the presence of a pituitary growth hormone (GH)-producing tumour, excessive secretion of growth hormone, raised levels of insulin-like growth factor I (IGF-I) and characteristic clinical presentation of acral enlargement. Over the past two decades, major advances have occurred in the understanding of some aspects of acromegaly--such as the biology of pituitary tumours, the physiology, molecular mechanisms of GH secretion and IGF-I generation, and the pathogenesis of comorbidities. Moreover, new approaches to diagnosis and surveillance (both in terms of screening and follow-up) of acromegaly have led to increases in the number of patients diagnosed with active disease, many of whom would previously have been missed. The development of sensitive assays for detecting plasma GH and IGF-I levels, as well as the widespread use of MRI for visualization of small tumours, have been major contributing factors to these improvements. Treatment advances have resulted in improved cure rates and disease control through novel neurosurgical techniques and pharmacological approaches. This Review summarizes and discusses the changes in our understanding of the epidemiology, diagnosis, treatment, and follow-up of acromegaly and its comorbidities.

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.

Intensity of pituitary adenoma on T2-weighted magnetic resonance imaging predicts the response to octreotide treatment in newly diagnosed acromegaly

BACKGROUND

Primary, preoperative medical treatment is an option in selected patients with acromegaly, but a subset of patients respond poorly. Valid prediction of response to somatostatin analogues (SA) might thus alter treatment stratification. The aims of this study were to assess whether T2 signal intensity could determine long-term response to first-line SA treatment and to assess clinical and biochemical baseline characteristics, as well as histological subtype in relation to the magnetic resonance imaging (MRI) appearances.

METHODS

In 45 newly diagnosed patients, T2-weighted signal intensity of the tumour was classified into hypo-, iso- or hyperintense. Biochemical and clinical baseline variables for the three groups were compared. In 25 patients primarily treated with long-acting SA for a median of 6 months [interquartile range (IQR):155-180 days], GH and IGF-1 reduction was assessed, and in 34 cases, immunohistochemical granulation pattern was evaluated.

RESULTS

The results showed that 12 (27%) adenomas were hypointense, 15 (33%) isointense and 18 (40%) hyperintense. Median IGF-1 [ratio IGF-1/ULN; (upper limit of normal)] was 3·5 (2·3-4·9), 2·9 (2·6-3·8) and 1·9 (1·3-2·6), respectively (P = 0·006 for difference between groups). Median GH values (μg/l) of a 3- to 5-point profile were 17·5 (6·1-35), 9·3 (6·0-32·5) and 4·1 (1·5-8·3), (P = 0·025). Median IGF-1 reduction (% of baseline) after first-line SA treatment was 51 (49-70), 36 (19-74) and 13 (5-42) (P = 0·03); median reduction in GH (% of baseline) was 86 (72-94), 78 (62-85) and 46 (1-70) (P = 0·02). T2 hyperintensity was associated with sparse granulation pattern on immunohistochemistry.

CONCLUSION

In patients with acromegaly, T2 signal intensity at diagnosis correlates with histological features and predicts biochemical outcome of first-line SA treatment.