Ectopic adrenocorticotropic hormone syndrome with Pneumocystis jirovecii pneumonia and pulmonary cryptococcosis: A case report and literature review.

Ectopic adrenocorticotropic hormone syndrome is a distinct subtype of endogenous Cushing's syndrome characterized by excessive cortisol secretion, which increases susceptibility to opportunistic infections. Herein, we present the case of a male patient in his early 40s who was admitted with fatigue and bilateral lower-extremity edema. Laboratory tests revealed markedly elevated serum adrenocorticotropic hormone and cortisol levels. Ectopic adrenocorticotropic hormone syndrome was confirmed via dexamethasone suppression testing and somatostatin receptor-targeted positron emission tomography-computed tomography, which localized an ectopic adrenocorticotropic hormone-secreting right pulmonary carcinoid tumor (a neuroendocrine tumor). During hospitalization, the patient was diagnosed with concurrent Pneumocystis jirovecii pneumonia and pulmonary cryptococcosis, and he responded favorably to trimethoprim-sulfamethoxazole and fluconazole. This case, supported by a review of the relevant literature, highlights the importance of early infection diagnosis, prompt management, and appropriate prophylaxis in patients with ectopic adrenocorticotropic hormone syndrome to improve prognosis.