A Rare Case of Ectopic ACTH Syndrome Most Likely Resulting From Metastatic Prostate Cancer

Ectopic adrenocorticotropic hormone (ACTH) syndrome is a rare condition accounting for approximately 10% of all Cushing syndrome cases. Herein, we present a rare case of ectopic ACTH syndrome most likely resulting from metastatic prostate cancer. A 40-year-old man with metastatic castration-resistant prostate adenocarcinoma presented with worsening left lower extremity edema. He received work-up for Cushing syndrome given his persistent hypokalemia and was diagnosed with ectopic ACTH syndrome. He was started on treatment with ketoconazole. Unfortunately, after discharge from the hospital, his clinical condition continued to deteriorate, and he elected to home hospice where he died.