Delayed Diagnosis of Ectopic Cushing Syndrome

Abstract

Here, we present the case of a 40-year-old man in whom the diagnosis of ectopic adrenocorticotropin (ACTH) syndrome went unrecognized despite evaluation by multiple providers until it was ultimately suspected by a nephrologist evaluating the patient for edema and weight gain. On urgent referral to endocrinology, screening for hypercortisolism was positive by both low-dose overnight dexamethasone suppression testing and 24-hour urinary free cortisol measurement. Plasma ACTH values confirmed ACTH-dependent Cushing syndrome. High-dose dexamethasone suppression testing was suggestive of ectopic ACTH syndrome. Inferior petrosal sinus sampling demonstrated no central-to-peripheral gradient, and ⁶⁸Ga-DOTATATE scanning revealed an avid 1.2-cm left lung lesion. The suspected source of ectopic ACTH was resected and confirmed by histopathology, resulting in surgical cure. While many patients with Cushing syndrome have a delayed diagnosis, this case highlights the critical need to increase awareness of the signs and symptoms of hypercortisolism and to improve the understanding of appropriate screening tests among nonendocrine providers.

Keywords: ACTH-dependent Cushing syndrome; ectopic ACTH; ectopic Cushing syndrome; glucocorticoid excess.

Figure 1.

Timeline of development of subjective symptoms and objective clinical findings preceding diagnosis and surgical cure of ectopic Cushing syndrome.

Figure 2.

Photographic representation of physical changes during the years leading up to diagnosis of ectopic Cushing syndrome in June 2021 and after surgical resection of culprit lesion.

Figure 3.

A, Precontrast and B, postcontrast T1-weighted sagittal magnetic resonance imaging of the sella. Images were affected by significant motion degradation, precluding clear visualization of the pituitary gland on coronal imaging.

Figure 4.

⁶⁸Ga-DOTATATE imaging. A, Coronal and B, axial views of the chest after administration of radiopharmaceutical. Arrow in both panels indicates DOTATATE-avid 1.2-cm left lung lesion.

Figure 5.

Lung tumor histopathology. A, The tumor was epicentered around a large airway (asterisk) and showed usual architecture for carcinoid tumor. B, The tumor cells had monomorphic nuclei with a neuroendocrine chromatin pattern, variably granulated cytoplasm, and a delicate background vascular network. By immunohistochemistry, the tumor cells were strongly positive for C, synaptophysin; D, CAM5.2; and E, adrenocorticotropin. F, Ki-67 proliferative index was extremely low (<1%).