Abrupt enlargement of adrenal incidentaloma: a case of isolated adrenal metastasis.

A 56-year-old Japanese man was referred for examination of right adrenal tumor (3 cm). He had no apparent preexisting cancer by radiological workup and accordingly, the patient was considered as a nonfunctioning adrenocortical adenoma and scheduled for periodic CT scans every 6 months. However, five months after the initial diagnosis the patient complained of severe right back pain with remarkable enlargement of both adrenals (~20-fold volume). Although the origin of adrenal tumor was uncertain by pathological workup, positron emission tomography (PET) scan with (18)F-2-fluoro-D-deoxyglucose (FDG) eventually revealed a hot spot on left upper lung, which was consistent with a lesion of thickened bulla wall observed by chest CT. The present case is a very rare example of abrupt enlargement of bilateral adrenals due to clinically isolated adrenal metastasis, suggesting the requirement of frequent observation with greatest care regarding morphologic changes of adrenal incidentalomas.