Somatostatin Receptor-negative and Fluorodeoxyglucose-positron Emission Tomography-positive Lung Neuroendocrine Tumor G1 Exhibiting Cyclic Cushing's Syndrome

• Published in: Internal Medicine Vol. 61; no. 24; pp. 9238-21 - 3698
• Main Authors: Nomura, Chiaki, Nakano, Yujiro, Tanaka, Takeo, Shima, Kosuke Robert, Kometani, Mitsuhiro, Kanamori, Takehiro, Ikeda, Hiroko, Takeshita, Yumie, Yoneda, Takashi, Takamura, Toshinari
• Format: Journal Article
• Language: English
• Published: Japan The Japanese Society of Internal Medicine 15.12.2022; Japan Science and Technology Agency
• Subjects: ACTH Syndrome, Ectopic - complications; ACTH-producing tumor; Adrenocorticotropic hormone; Aged; Carcinoid Tumor - surgery; Carcinoma, Neuroendocrine - complications; Case Report; Cushing syndrome; Cushing Syndrome - complications; Cushing Syndrome - etiology; cyclic; FDG-PET; Female; Fluorodeoxyglucose F18; Humans; Hyperglycemia; Hypokalemia; Internal medicine; Localization; Lung - pathology; Lung Neoplasms - complications; Lung Neoplasms - diagnostic imaging; Nervous system diseases; Neuroendocrine tumors; Neuroendocrine Tumors - complications; Neuroendocrine Tumors - diagnostic imaging; Neuroendocrine Tumors - surgery; Pituitary; Positron emission tomography; Receptors, Somatostatin; Remission; Scintigraphy; Somatostatin; Somatostatin receptors; somatostatin-receptor; FDG-PET; ACTH-producing tumor; somatostatin-receptor; cyclic
• ISSN: 0918-2918; 1349-7235
• DOI: 10.2169/internalmedicine.9238-21

Localization of ectopic cyclic Cushing's syndrome, which causes life-threatening complications, is challenging. A 70-year-old woman showed cyclic hypokalemia and hyperglycemia and was diagnosed with cyclic ectopic Cushing's syndrome. Although somatostatin-receptor scintigraphy failed to localize the responsible tumor, fluorodeoxyglucose-positron emission tomography (FDG-PET) showed the uptake of tracer in a lung tumor. Lobectomy resulted in remission. The resected ACTH-producing neuroendocrine tumor had Ki-67<2% and negative staining for somatostatin receptors. This is the first case assessed both radiological findings and pathological findings in cyclic ectopic Cushing's syndrome. Subsequent FDG-PET is recommended if somatostatin-receptor scintigraphy is negative.