Ectopic Cushing's syndrome from a corticotropin-releasing hormone-secreting medullary thyroid carcinoma: a rare pitfall of inferior petrosal sinus sampling

Vivi-Nelli Mäkinen*, Stine Horskær Madsen, Mette Ji Riis-Vestergaard, Mette Bjerre, Steen Bønløkke Pedersen, Sylvia L Asa, Lars Rolighed, Jens Otto Lunde Jørgensen, Marie Juul Ornstrup

*Corresponding author af dette arbejde

Publikation: Bidrag til tidsskrift/Konferencebidrag i tidsskrift /Bidrag til avisTidsskriftartikelForskningpeer review

Abstract

SUMMARY: This case report describes a rare presentation of ectopic Cushing's syndrome (CS) due to ectopic corticotropin-releasing hormone (CRH) production from a medullary thyroid carcinoma (MTC). The patient, a 69-year-old man, presented with symptoms of muscle weakness, facial plethora, and easy bruising. An inferior petrosal sinus sampling test (IPSS) demonstrated pituitary adrenocorticotrophic hormone (ACTH) secretion, but a whole-body somatostatin receptor scintigraphy (68Ga-DOTATOC PET/CT) revealed enhanced uptake in the right thyroid lobe which, in addition to a grossly elevated serum calcitonin level, was indicative of an MTC. A 18F-DOPA PET/CT scan supported the diagnosis, and histology confirmed the presence of MTC with perinodal growth and regional lymph node metastasis. On immunohistochemical analysis, the tumor cell stained positively for calcitonin and CRH but negatively for ACTH. Distinctly elevated plasma CRH levels were documented. The patient therefore underwent thyroidectomy and bilateral adrenalectomy. This case shows that CS caused by ectopic CRH secretion may masquerade as CS due to a false positive IPSS test. It also highlights the importance of considering rare causes of CS when diagnostic test results are ambiguous.

LEARNING POINTS: Medullary thyroid carcinoma may secrete CRH and cause ectopic CS. Ectopic CRH secretion entails a rare pitfall of inferior petrosal sinus sampling yielding a false positive test. Plasma CRH measurements can be useful in selected cases.

OriginalsprogEngelsk
Artikelnummer23-0057
TidsskriftEndocrinology, Diabetes & Metabolism Case Reports
Vol/bind2023
Nummer3
ISSN2052-0573
DOI
StatusUdgivet - jul. 2023

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