Adrenal oncocytoma: a rare presentation of a benign 18F-fluorodeoxyglucose PET avid virilising adrenal tumour.

A woman in her 70s presented with features of hyperandrogenism including clitoral enlargement and deepening of her voice. Biochemical investigations revealed raised plasma androgens and urinary androgen metabolites and imaging findings showed a highly F-18 fluorodeoxyglucose (FDG)-PET avid left adrenal tumour initially suspected to be a malignant adrenocortical carcinoma (ACC). She subsequently underwent an uncomplicated laparoscopic adrenalectomy where complete resection of her tumour was achieved. Histopathological analysis demonstrated a benign adrenal oncocytoma with no evidence of malignancy. This case illustrates a rare presentation of a functioning virilising adrenal oncocytoma as a benign mimic of ACC.