Chronic necrotising aspergillosis mimicking ACTH-secreting tumour in a case of Cushing's disease

An 18-year-old man presenting with speech and behaviour disorders was found to suffer from Cushing's syndrome. Ectopic ACTH secretion was initially suspected on the basis of very high cortisoluria and ACTH concentrations, severe hypokalemia, a lung hypermetabolic lesion and a normal pituitary on conventional magnetic resonance imaging (MRI). After lung surgery, this lesion proved to be chronic necrotising aspergilloosis (CNA). Diagnostic reevaluation by bilateral inferior petrosal sinus sampling disclosed a right-sided petrosal sinus gradient consistent with Cushing's disease (CD). A new high resolution thin-section MRI demonstrated a 5 mm pituitary adenoma, which could be removed successfully. Thus, a lung mass associated with several clues in favour of ectopic ACTH secretion may hide a diagnosis of CD. Such a mass can be CNA, an opportunistic infection favoured by immunosuppression, which to our knowledge, is the first case reported in CD.