Malignant pituitary corticotroph adenomas: report of two cases and a comprehensive review of the literature

From Nelson's Syndrome to Corticotroph Tumor Progression Speed: An Update

Since the first description of Nelson syndrome 60 years ago, the way to consider corticotroph pituitary neuroendocrine tumors (PitNETs) after bilateral adrenalectomy has evolved. Today, it is globally acknowledged that only a subset of corticotroph PitNETs is aggressive.After adrenalectomy, corticotroph tumor progression (CTP) occurs in about 30 to 40% of patients during a median follow-up of 10 years. When CTP occurs, various CTP speeds (CTPS) can be observed. Using simple metrics in patients with CTP, CTPS was reported to vary from a few millimeters to up to 40 mm per year. Rapid CTPS/ Nelson's syndrome was associated with more severe Cushing's disease, higher adrenocorticotropic hormone (ACTH) in the year following adrenalectomy, and higher Ki67 on pituitary pathology. Complications such as apoplexy, cavernous syndrome, and visual defects were associated with higher CTPS. During follow-up, early morning ACTH, absolute variations properly reflected CTPS. Finally, CTPS was not higher after than before adrenalectomy, suggesting that cortisol deprivation after adrenalectomy does not impact CTPS in a majority of patients.Taken together, rapid CTPS/ Nelson's syndrome probably reflects the intrinsic aggressiveness of some corticotroph PitNETs. The precise molecular mechanisms related to corticotroph PitNET aggressiveness remain to be deciphered. Regular MRIs combined with intermediate morning ACTH measurements probably provide a reliable way to detect early and manage fast-growing tumors and, therefore, limit the complications.

Aggressive Pituitary Tumors and Pituitary Carcinomas: From Pathology to Treatment

Aggressive pituitary tumors (APTs) and pituitary carcinomas (PCs) are heterogeneous with regard to clinical presentation, proliferative markers, clinical course, and response to therapy. Half of them show an aggressive course only many years after the first apparently benign presentation. APTs and PCs share several properties, but a Ki67 index greater than or equal to 10% and extensive p53 expression are more prevalent in PCs. Mutations in TP53 and ATRX are the most common genetic alterations; their detection might be of value for early identification of aggressiveness. Treatment requires a multimodal approach including surgery, radiotherapy, and drugs. Temozolomide is the recommended first-line chemotherapy, with response rates of about 40%. Immune checkpoint inhibitors have emerged as second-line treatment in PCs, with currently no evidence for a superior effect of dual therapy compared to monotherapy with PD-1 blockers. Bevacizumab has resulted in partial response (PR) in few patients; tyrosine kinase inhibitors and everolimus have generally not been useful. The effect of peptide receptor radionuclide therapy is limited as well. Management of APT/PC is challenging and should be discussed within an expert team with consideration of clinical and pathological findings, age, and general condition of the patient. Considering that APT/PCs are rare, new therapies should preferably be evaluated in shared standardized protocols. Prognostic and predictive markers to guide treatment decisions are needed and are the scope of ongoing research.

Temozolomide therapy for aggressive pituitary tumours - current understanding and future perspectives

The use of temozolomide (TMZ) for the management of aggressive pituitary tumours (APT) has revolutionised clinical practice in this field with significantly improved clinical outcomes and long-term survival. Its use is now well established however a large number of patients do not respond to treatment and recurrence after cessation of TMZ is common. A number of challenges remain for clinicians such as appropriate patient selection, treatment duration and the role of combination therapy. This review will examine the use of TMZ to treat APT including mechanism of action, treatment regimen and duration; biomarkers predicting response to treatment and patient selection; and current evidence for administration of TMZ in combination with other agents.

European Society of Endocrinology Clinical Practice Guidelines for the management of aggressive pituitary tumours and carcinomas

BACKGROUND

Pituitary tumours are common and easily treated by surgery or medical treatment in most cases. However, a small subset of pituitary tumours does not respond to standard medical treatment and presents with multiple local recurrences (aggressive pituitary tumours) and in rare occasion with metastases (pituitary carcinoma). The present European Society of Endocrinology (ESE) guideline aims to provide clinical guidance on diagnosis, treatment and follow-up in aggressive pituitary tumours and carcinomas.

METHODS

We decided upfront, while acknowledging that literature on aggressive pituitary tumours and carcinomas is scarce, to systematically review the literature according to the GRADE (Grading of Recommendations Assessment, Development and Evaluation) system. The review focused primarily on first- and second-line treatment in aggressive pituitary tumours and carcinomas. We included 14 single-arm cohort studies (total number of patients = 116) most on temozolomide treatment (n = 11 studies, total number of patients = 106). A positive treatment effect was seen in 47% (95% CI: 36-58%) of temozolomide treated. Data from the recently performed ESE survey on aggressive pituitary tumours and carcinomas (165 patients) were also used as backbone for the guideline. SELECTED RECOMMENDATION: (i) Patients with aggressive pituitary tumours should be managed by a multidisciplinary expert team. (ii) Histopathological analyses including pituitary hormones and proliferative markers are needed for correct tumour classification. (iii) Temozolomide monotherapy is the first-line chemotherapy for aggressive pituitary tumours and pituitary carcinomas after failure of standard therapies; treatment evaluation after 3 cycles allows identification of responder and non-responder patients. (iv) In patients responding to first-line temozolomide, we suggest continuing treatment for at least 6 months in total. Furthermore, the guideline offers recommendations for patients who recurred after temozolomide treatment, for those who did not respond to temozolomide and for patients with systemic metastasis.

Case report: ACTH-secreting pituitary carcinoma metastatic to the liver in a patient with a history of atypical pituitary adenoma and Cushing's disease

Background

Pituitary carcinoma is a rare entity requiring the presence of metastasis to confirm its malignant potential. We report a case of pituitary carcinoma and discuss the diagnosis and management of this lesion in relation to the existing literature.

Case presentation

The patient is a 51-year-old woman with Cushing’s disease and intact adrenal glands who was diagnosed with metastatic pituitary carcinoma to the liver, 29 months after initial resection of an ACTH-secreting primary atypical pituitary adenoma (APA). Prior to detection of this metastasis the patient underwent repeat resection and radiotherapy for residual cavernous sinus disease. The metastatic lesion was detected by interval surveillance of serum ACTH and 24-hour urine cortisol, which despite stable pituitary MRI, were significantly elevated. These abnormalities prompted a PET scan that demonstrated hypermetabolic liver parenchyma, which was suspicious for metastasis on abdominal MRI. An ultrasound-guided liver biopsy demonstrated nests of moderately-differentiated cells with intermediate-sized, monotonous nuclei, distinct nucleoli, and abundant basophilic cytoplasm, confirmed by immunohistochemistry to represent metastatic pituitary carcinoma. The liver lesion was subsequently successfully removed by wedge resection. One year later, the patient’s residual cavernous sinus disease grew markedly, and she was placed on dual-agent chemotherapy consisting of oral temozolomide and capecitabine, with stabilization of her intracranial disease to present, although liver metastases recurred.

Conclusions

Pituitary carcinoma is a rare entity impossible to recognize as a primary tumor because its diagnosis by definition requires the presence of metastasis. Maintaining awareness of the entity and its precursor lesion APA is essential for its accurate pathologic diagnosis and appropriate management.

Drop metastasis of adrenocorticotropic hormone-producing pituitary carcinoma to the cauda equina

The diagnosis of pituitary carcinoma cannot be made easily histologically, and most cases of pituitary carcinoma are diagnosed only after the clinical detection of metastasis. Distant metastasis of pituitary tumor occurs in 0.1% to 0.2% of cases and has been reported in the liver, bone and central nervous system, with only one case of metastasis to the cauda equine reported. This study describes a rare case of the drop metastasis of adrenocorticotropic hormone-producing pituitary adenocarcinoma to the cauda equina, causing cauda equina syndrome.

Molecular basis of pharmacological therapy in Cushing's disease

Cushing's disease (CD) is a severe endocrine condition caused by an adrenocorticotropin (ACTH)-producing pituitary adenoma that chronically stimulates adrenocortical cortisol production and with potentially serious complications if not or inadequately treated. Active CD may produce a fourfold increase in mortality and is associated with significant morbidities. Moreover, excess mortality risk may persist even after CD treatment. Although predictors of risk in treated CD are not fully understood, the importance of early recognition and adequate treatment is well established. Surgery with resection of a pituitary adenoma is still the first line therapy, being successful in about 60-70 % of patients; however, recurrence within 2-4 years may often occur. When surgery fails, medical treatment can reduce cortisol production and ameliorate clinical manifestations while more definitive therapy becomes effective. Compounds that target hypothalamic-pituitary axis, glucocorticoid synthesis or adrenocortical function are currently used to control the deleterious effects of chronic glucocorticoid excess. In this review we describe and analyze the molecular basis of the drugs targeting the disease at central level, suppressing ACTH secretion, as well as at peripheral level, acting as adrenal inhibitors, or glucocorticoid receptor antagonists. Understanding of the underlying molecular mechanisms in CD and of glucocorticoid biology should promote the development of new targeted and more successful therapies in the future. Indeed, most of the drugs discussed have been tested in limited clinical trials, but there is potential therapeutic benefit in compounds with better specificity for the class of receptors expressed by ACTH-secreting tumors. However, long-term follow-up with management of persistent comorbidities is needed even after successful treatment of CD.

Invasive adenoma and pituitary carcinoma: a SEER database analysis

Invasive pituitary adenomas and pituitary carcinomas are clinically indistinguishable until identification of metastases. Optimal management and survival outcomes for both are not clearly defined. The purpose of this study is to use the Surveillance, Epidemiology, and End Results (SEER) database to report patterns of care and compare survival outcomes in a large series of patients with invasive adenomas or pituitary carcinomas. One hundred seventeen patients diagnosed between 1973 and 2008 with pituitary adenomas/adenocarcinomas were included. Eighty-three invasive adenomas and seven pituitary carcinomas were analyzed for survival outcomes. Analyzed prognostic factors included age, sex, race, histology, tumor extent, and treatment. A significant decrease in survival was observed among carcinomas compared to invasive adenomas at 1, 2, and 5 years (p = 0.047, 0.001, and 0.009). Only non-white race, male gender, and age ≥65 were significant negative prognostic factors for invasive adenomas (p = 0.013, 0.033, and <0.001, respectively). There was no survival advantage to radiation therapy in treating adenomas at 5, 10, 20, or 30 years (p = 0.778, 0.960, 0.236, and 0.971). In conclusion, pituitary carcinoma patients exhibit worse overall survival than invasive adenoma patients. This highlights the need for improved diagnostic methods for the sellar phase to allow for potentially more aggressive treatment approaches.

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.

Chemotherapy-induced regression of an adrenocorticotropin-secreting pituitary carcinoma accompanied by secondary adrenal insufficiency

Purpose. Adrenocorticotropin- (ACTH-) secreting pituitary carcinomas are rare and require multimodality treatment. The aim of this study was to report the response to various therapies and discuss the potential development of secondary adrenal insufficiency with cytotoxic chemotherapy. Methods. This report describes a man with a large silent corticotroph adenoma progressing to endogenous hypercortisolism and metastatic ACTH-secreting pituitary carcinoma over a period of 14 years. Results. Seven years after initial presentation, progressive tumor enlargement associated with the development of hypercortisolism mandated multiple pituitary tumor debulking procedures and radiotherapy. Testing of the Ki-67 proliferation index was markedly high and he developed a hepatic metastasis. Combination therapy with cisplatin and etoposide resulted in a substantial reduction in tumor size, near-complete regression of his liver metastasis, and dramatic decrease in ACTH secretion. This unexpectedly resulted in symptomatic secondary adrenal insufficiency. Conclusions. This is the first reported case of secondary adrenal insufficiency after use of cytotoxic chemotherapy for metastatic ACTH-secreting pituitary carcinoma. High proliferative indices may be predictive of dramatic responses to chemotherapy. Given the potential for such responses, the development of secondary adrenal insufficiency may occur and patients should be monitored accordingly.

Temozolomide responsiveness in aggressive corticotroph tumours: a case report and review of the literature

Pituitary carcinoma occurs in ~0.2% of resected pituitary tumours and carries a poor prognosis (mean survival <4 years), with standard chemotherapy regimens showing limited efficacy. Recent evidence suggests that temozolomide (TMZ), an orally-active alkylating agent used principally in the management of glioblastoma, may also be effective in controlling aggressive/invasive pituitary adenomas/carcinomas. A low level of expression of the DNA-repair enzyme O6-methylguanine-DNA methyltransferase (MGMT) predicts TMZ responsiveness in glioblastomas, and a similar correlation has been observed in the majority of aggressive pituitary adenomas/carcinomas reported to date. Here, we report a case of a silent pituitary corticotroph adenoma, which subsequently re-presented with Cushing's syndrome due to functioning hepatic metastases. The tumour exhibited low immunohistochemical MGMT expression in both primary (pituitary) and secondary (hepatic) lesions. Initial TMZ therapy (200 mg/m² for 5 days every 28 days-seven cycles) resulted in marked clinical, biochemical [>50% fall in adrenocorticotrophic hormone (ACTH)] and radiological [partial RECIST (response evaluation criteria in solid tumors) response] improvements. The patient then underwent bilateral adrenalectomy. However, despite reintroduction of TMZ therapy (further eight cycles) ACTH levels plateaued and no further radiological regression was observed. We review the existing literature reporting TMZ efficacy in pituitary corticotroph tumours, and highlight the pointers/lessons for treating aggressive pituitary neoplasia that can be drawn from experience of susceptibility and evolving resistance to TMZ therapy in glioblastoma. Possible strategies for mitigating resistance developing during TMZ treatment of pituitary adenomas/carcinomas are also considered.

Pituitary carcinoma recurrent to the lumbar intradural extramedullary space: case report

CONTEXT

Pituitary tumors are rare, and pituitary carcinomas are rarer still. Prognosis is poor, with less than 50% of patients surviving past 1 year after diagnosis. In this case of spinal metastasis from an adrenocorticotropic hormone-secreting pituitary carcinoma, the intradural extramedullary metastases recurred in the same lumbar area 6 years apart.

FINDINGS

Fourteen years prior to presentation in our clinic, a 48-year-old woman was diagnosed with pituitary adenoma which was treated with resection followed by radiation. Eight years later, an intradural extramedullary spinal drop metastasis at L2-L3 was again treated with resection and radiation. Three years later, magnetic resonance imaging (MRI) revealed a mass encasing the right carotid artery, which was treated for 1 year with chemotherapy using temozolomide (Temodar). Three years later, MRI showed intradural extramedullary metastases at the L3-L4 intervertebral disc space and behind the L3 vertebral body; treatment was again resection followed by radiation. Back pain and weakness resolved after surgery and her neurological examination returned to baseline. There was no evidence of recurrence 1 year after surgery.

CONCLUSION/CLINICAL RELEVANCE

In this unusual case, this pituitary carcinoma metastasized twice in 6 years to virtually the same intradural extramedullary lumbar region. Surgical resection of these masses aided in relieving neurological symptoms and prolonging life.

Atypical pituitary adenoma with malignant features

Pituitary carcinoma is characterized by the presence of systemic or central nervous system metastases rather than malignant histological features, making it an anomaly amongst carcinomas. In contrast, aggressive or atypical pituitary adenomas often have a relatively bland histological appearance despite their malignant growth patterns. We now report a case of a 67-years-old male with a giant pituitary tumor with overt pathologic and phenotypic features of malignancy, but the absence of metastases, that evolved from a benign non-functioning gonadotroph macroadenoma treated 10 years earlier. This case represents the first report of a pituitary adenoma with overt malignant histology that does not meet criteria for classification as pituitary carcinoma, helping to complete the pathological spectrum of disease observed with pituitary tumors.