Occult ectopic ACTH syndrome presenting with pulmonary nocardiosis and cognitive decline in a vulnerable patient.

A woman in her early 60s with a remote history of lung cancer presented with severe hypercortisolism, bilateral pulmonary consolidations and progressive cognitive decline. Extensive imaging and biopsies failed to identify a definitive adrenocorticotropic hormone (ACTH)-secreting tumour, but pulmonary nocardiosis was diagnosed, reflecting profound cortisol-induced immunosuppression. Management was further complicated by limited social supports and a history of unstable housing, raising concerns about access to advanced imaging and reliable follow-up. Despite medical therapy, hypercortisolism persisted, and she ultimately underwent bilateral adrenalectomy with marked improvement. This case illustrates the challenges of occult ectopic ACTH syndrome and underscores the importance of multidisciplinary management.