Pitfall of the accessory spleen.

Two patients, one with insulinoma and one with Cushing's syndrome, are presented. Biochemical evaluation readily suggested the correct diagnosis. During radiologic imaging, the anatomic abnormality giving rise to these diseases, i.e. a pancreatic islet cell tumor, and an adrenal adenoma, at first were mistakenly interpreted as an accessory spleen on the basis of specific computed tomography and magnetic resonance imaging appearances. The insulinoma was identified as such during laparotomy, whereas additional jodo-cholesterol scintigraphy revealed the real nature of the lesion in the patient with Cushing's syndrome. Both patients were operated successfully.