Adrenocorticotropic Hormone-Producing Paraganglioma With Low Plasma ACTH Level: A Case Report and Review of the Literature.

Ectopic adrenocorticotropic hormone (ACTH) syndrome caused by paraganglioma is extremely rare. It usually accompanied by high or normal plasma ACTH level. Here we described a male who presented with ectopic ACTH-producing paraganglioma and a low plasma ACTH level. Immunohistochemistry and immunofluorescence confirmed ACTH production in focal paraganglioma cells. This unusual case expanded the spectrum of ACTH-dependent Cushing's syndrome and revealed a potential mechanism of this unique clinical phenotype. Besides, the literature concerning ACTH-producing paraganglioma is reviewed.