Corticotropic cell

Differential diagnosis

Cushing's disease

ACTH secretion

Cushing syndrome

Pituitary gland

Internal medicine

Adrenocorticotropic hormone

Hormone

Medicine

Disease

Pathology

Endocrinology and Metabolism Clinics of North America

Despite modern imaging techniques, differentiating ectopic adrenocorticotropic hormone (ACTH) syndrome from pituitary-dependent Cushing’s syndrome, Cushing’s disease, is especially difficult when well-differentiated carcinoids are the source of ACTH secretion, particularly pulmonary carcinoid tumors. ACTH-secreting pulmonary carcinoids, like the corticotroph adenomas causing Cushing’s disease, are often small and difficult to detect, and patients present with a gradual onset of the classical signs and symptoms of Cushing’s syndrome, indistinguishable from the presentation of Cushing’s disease. Hence, the differential diagnosis relies on a combination of clinical assessment, dynamic biochemical tests, inferior petrosal sinus sampling, and multimodal imaging, each with its own caveats and pitfalls.

The Ectopic Adrenocorticotropic Hormone Syndrome