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

Intern Med. 2022 Dec 15;61(24):3693-3698. doi: 10.2169/internalmedicine.9238-21. Epub 2022 May 31.

Abstract

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 adrenocorticotropic hormone (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.

Keywords: ACTH-producing tumor; FDG-PET; cyclic; somatostatin-receptor.

Publication types

  • Case Reports

MeSH terms

  • ACTH Syndrome, Ectopic* / complications
  • Aged
  • Carcinoid Tumor* / surgery
  • Carcinoma, Neuroendocrine* / complications
  • Cushing Syndrome* / complications
  • Cushing Syndrome* / etiology
  • Female
  • Fluorodeoxyglucose F18
  • Humans
  • Lung / pathology
  • Lung Neoplasms* / complications
  • Lung Neoplasms* / diagnostic imaging
  • Neuroendocrine Tumors* / complications
  • Neuroendocrine Tumors* / diagnostic imaging
  • Neuroendocrine Tumors* / surgery
  • Positron-Emission Tomography
  • Receptors, Somatostatin
  • Somatostatin

Substances

  • Receptors, Somatostatin
  • Fluorodeoxyglucose F18
  • Somatostatin