Multi-step approach in a complex case of Cushing's syndrome and medullary thyroid carcinoma

Functional imaging in ectopic Cushing syndrome

PURPOSE OF REVIEW

Ectopic adrenocorticotropic hormone (ACTH)-secreting tumors are commonly small, yet they often lead to fulminant forms of Cushing syndrome. High-resolution functional imaging modalities, such as [Ga]-DOTATATE, have been recently introduced in clinical practice for the identification of neuroendocrine tumors. In this review, we focus on the performance of [Ga]-DOTATATE as a tool for localizing primary and metastatic sources of ectopic Cushing syndrome (ECS).

RECENT FINDINGS

Prompt surgical removal of ectopic ACTH-secreting tumors is the mainstay of therapy in patients with ECS. Detecting such tumors with conventional cross-sectional imaging is often unsuccessful, owing to their small size. [Ga]-DOTATATE has been approved in 2016 by the Federal Drug Administration for imaging well differentiated neuroendocrine tumors. Data regarding the performance of [Ga]-DOTATATE for detecting ectopic ACTH-secreting tumors remain limited, in part owing to the recent introduction of this imaging modality in clinical practice, and in part because of the low prevalence of ECS. Nevertheless, [Ga]-DOTATATE has been reported to be useful in identifying primary and metastatic ectopic ACTH-secreting lesions that were not apparent on other imaging studies, impacting the clinical care of many patients with ECS.

SUMMARY

[Ga]-DOTATATE-based imaging, which targets the somatostatin receptors abundantly expressed in neuroendocrine tumors, has generally high, although variable resolution in detecting the source(s) of ECS.

Ectopic cushing's syndrome due to corticotropin releasing hormone

Cushing's syndrome (CS) secondary to corticotropin releasing hormone (CRH) producing tumors is rare. In this paper we present an Iranian patient who was admitted to our hospital with classic signs and symptoms of CS. Laboratory evaluation revealed high serum and urine cortisol which could not be suppressed with dexamethasone. Abdominal CT scan revealed a mass in abdominal cavity. A percutaneous needle biopsy was performed and histopathologic evaluation revealed that the mass was a neuroendocrine tumor. A multi-disciplinary approach including resection of the mass, bilateral adrenalectomy somatostatin analogue and chemotherapy was applied for management of the disease. Extensive review of English literature focusing on the topic from 1971 to 2018 revealed that there have been only 75 similar cases. Clinical, laboratory, imaging, histopathologic characteristics and managements of these patients will also be discussed in this paper.

Phaeochromocytoma and ACTH-dependent cushing's syndrome: tumour crf secretion can mimic pituitary cushing's disease

INTRODUCTION

10% of corticotrophin (ACTH)-dependent Cushing's syndrome arises from secretion by extrapituitary tumours, with phaeochromocytoma implicated in a few cases. Ectopic secretion by phaeochromocytoma of corticotropin-releasing hormone (CRF), with secondary corticotroph hyperplasia, is even rarer, with only five cases in the literature hitherto. However, such cases may be classified as 'ectopic ACTH' due to incomplete verification.

CLINICAL CASES

We describe three patients with phaeochromocytoma and ACTH-dependent Cushing's syndrome in whom biochemical cure was achieved following unilateral adrenalectomy. Although unable to access a validated CRF assay within the timeframe for sample storage, we nevertheless inferred CRF secretion in 2 of 3 cases by tumour immunostaining (positive for CRF; negative for ACTH), supported in one case by pre-operative inferior petrosal sinus sampling (IPSS) indicative of pituitary ACTH source. Both cases were characterized by rapid postoperative wean off glucocorticoids, presumed to reflect the pituitary stimulatory-effect of CRF outweighing central negative feedback inhibition by hypercortisolaemia. By contrast, the tumour excised in a third case exhibited positive immunostaining for ACTH - negative for CRF - and postoperative recovery of hypothalamic-pituitary-adrenal axis took significantly longer.

DISCUSSION

Ectopic CRF production is biochemically indistinguishable from ectopic ACTH secretion, except that IPSS mimics pituitary Cushing's disease and cortisol dynamics may normalize rapidly postadrenalectomy. CRF secretion can be inferred through tumour immunohistochemistry, even if no CRF assay is available. Unrecognized phaeochromocytoma ACTH secretion may underpin some cases of cardiovascular collapse postadrenalectomy through acute hypocortisolaemia. Despite advances in phaeochromocytoma genetics since previous reports, we were unable to identify somatic DNA defects associated with either ACTH or CRF secretion.

Possible ACTH-independent, cortisol-secreting and DHEA-secreting metastatic hepatocellular carcinoma causing Cushing's syndrome

Cortisol production by hepatocellular carcinoma (HCC) has not been previously reported and dehydroepiandrosterone (DHEA) secretion by HCC is rare. We report a case of a 53-year-old woman admitted with dyspnoea and headache. Serum cortisol by immunoassay (IA) was 42.3 μg/dL, urine free cortisol (UFC) by liquid chromatography mass spectrometry (LC/MS/MS) was 106.1 μg/24 h, serum DHEA by LC/MS/MS was 4886 ng/mL, serum DHEA-S by LC/MS/MS was 4477 ng/mL and plasma adrenocorticotrophic hormone (ACTH) by IA was 10 pg/mL. CT showed likely HCC metastatic to the left adrenal gland, brain and lungs. Liver and adrenal gland biopsies confirmed HCC. ACTH tumour staining was negative. High serum and UFC levels and high serum DHEA and DHEA-S with low-normal plasma ACTH and negative tumour ACTH staining suggested ACTH-independent ectopic Cushing's syndrome (CS); cortisol and DHEA being likely secreted by the HCC. To the best of our knowledge, this is the first reported case of HCC associated with CS.

Conventional and Nuclear Medicine Imaging in Ectopic Cushing's Syndrome: A Systematic Review

CONTEXT

Ectopic Cushing's Syndrome (ECS) can be a diagnostic challenge with the hormonal source difficult to find. This study analyzes the accuracy of imaging studies in ECS localization.

EVIDENCE ACQUISITION

Systematic review of medical literature for ECS case series providing individual patient data on at least one conventional imaging technique (computed tomography [CT]/magnetic resonance imaging) and one of the following: 111In-pentetreotide (OCT), 131I/123I-metaiodobenzylguanidine, 18Ffluoro-2-deoxyglucose-positron emission tomography (FDG-PET), 18F-fluorodopa-PET (F-DOPA-PET), 68Ga- DOTATATE-PET/CT or 68Ga-DOTATOC-PET/CT scan (68Gallium-SSTR-PET/CT).

EVIDENCE SUMMARY

The analysis comprised 231 patients (females, 50.2%; age, 42.617 y). Overall, 52.4%(121/231) had "overt" ECS,18.6% had "occult" ECS, and 29% had "covert" ECS. Tumors were located in the lung (55.3%), mediastinum-thymus (7.9%), pancreas (8.5%), adrenal glands (6.4%), gastrointestinal tract (5.4%), thyroid (3.7%), and other sites (12.8%), and primary tumors were mostly bronchial neuroendocrine tumors (NETs) (54.8%), pancreatic NETs (8%), mediastinum-thymus NETs (6.9%), gastrointestinal NETs (5.3%), pheochromocytoma (6.4%), neuroblastoma (3.2%), and medullary thyroid carcinoma (3.2%). Tumors were localized byCTin66.2%(137/207), magnetic resonance imaging in 51.5% (53/103), OCT in 48.9% (84/172), FDG-PET in 51.7% (46/89), F-DOPAPET in 57.1% (12/21), 131/123I-metaiodobenzylguanidine in 30.8% (4/13), and 68Gallium-SSTRPET/CT in 81.8% (18/22) of cases. Molecular imaging discovered 79.1% (53/67) of tumors unidentified by conventional radiology, with OCT the most commonly used, revealing the tumor in 64%, followed by FDG-PET in 59.4%. F-DOPA-PET was used in only seven covert cases (sensitivity, 85.7%). Notably, 68Gallium-SSTR-PET/CT had 100% sensitivity among covert cases.

CONCLUSIONS

Nuclear medicine improves the sensitivity of conventional radiology when tumor site identification is problematic. OCT offers a good availability/reliability ratio, and FDG-PET was proven useful. 68Gallium-SSTR-PET/CT use was infrequent, despite offering the highest sensitivity.

The role of inferior petrosal sinus sampling in ACTH-dependent Cushing's syndrome: review and joint opinion statement by members of the Italian Society for Endocrinology, Italian Society for Neurosurgery, and Italian Society for Neuroradiology

In the management of adrenocorticotropic hormone (ACTH)–dependent Cushing's syndrome, inferior petrosal sinus sampling (IPSS) provides information for the endocrinologist, the neurosurgeon, and the neuroradiologist. To the endocrinologist who performs the etiological diagnosis, results of IPSS confirm or exclude the diagnosis of Cushing's disease with 80%–100% sensitivity and over 95% specificity. Baseline central-peripheral gradients have suboptimal accuracy, and stimulation with corticotropin-releasing hormone (CRH), possibly desmopressin, has to be performed. The rationale for the use of IPSS in this context depends on other diagnostic means, taking availability of CRH and reliability of dynamic testing and pituitary imaging into account. As regards the other specialists, the neuroradiologist may collate results of IPSS with findings at imaging, while IPSS may prove useful to the neurosurgeon to chart a surgical course. The present review illustrates the current standpoint of these 3 specialists on the role of IPSS.

Ectopic corticotropin-releasing hormone (CRH) syndrome from metastatic small cell carcinoma: a case report and review of the literature

BACKGROUND

Cushing's Syndrome (CS) which is caused by isolated corticotropin-releasing hormone (CRH) production, rather than adrenocorticotropin (ACTH) production, is extremely rare.

METHODS

We describe the clinical presentation, course, laboratory values and pathologic findings of a patient with isolated ectopic CRH causing CS. We review the literature of the types of tumors associated with this unusual syndrome and the behavior of these tumors by endocrine testing.

RESULTS

A 56 year old woman presented with clinical and laboratory features consistent with ACTH-dependent CS. Pituitary imaging was normal and cortisol did not suppress with a high dose dexamethasone test, consistent with a diagnosis of ectopic ACTH. CT imaging did not reveal any discrete lung lesions but there were mediastinal and abdominal lymphadenopathy and multiple liver lesions suspicious for metastatic disease. Laboratory testing was positive for elevated serum carcinoembryonic antigen and the neuroendocrine marker chromogranin A. Serum markers of carcinoid, medullary thyroid carcinoma, and pheochromocytoma were in the normal range. Because the primary tumor could not be identified by imaging, biopsy of the presumed metastatic liver lesions was performed. Immunohistochemistry was consistent with a neuroendocrine tumor, specifically small cell carcinoma. Immunostaining for ACTH was negative but was strongly positive for CRH and laboratory testing revealed a plasma CRH of 10 pg/ml (normal 0 to 10 pg/ml) which should have been suppressed in the presence of high cortisol.

CONCLUSIONS

This case illustrates the importance of considering the ectopic production of CRH in the differential diagnosis for presentations of ACTH-dependent Cushing's Syndrome.

Simultaneous ectopic adrenocorticotropic hormone syndrome and adrenal metastasis of a medullary thyroid carcinoma causing paraneoplastic Cushing's syndrome

Medullary thyroid carcinomas (MTC) constitute about 5 to 7 % of thyroid neoplasms. They originate from parafollicular C-cells which can secrete adrenocorticotropic hormone (ACTH) and/or corticotropin-releasing factor (CRF) in abnormally high concentrations, potentially causing paraneoplastic Cushing's Syndrome (CS). We report on a 42-year-old male patient with a ten year history of metastatic medullary thyroid carcinoma suffering from paraneoplastic Cushing's Syndrome caused by ectopic hypersecretion of ACTH and a simultaneous Cortisol producing adrenal metastasis.