Myelolipoma of the renal sinus. An unusual site for a rare extra- adrenal lesion.

Extra-adrenal myelolipomas are rare; approximately 36 cases have been reported to date. We document a case of myelolipoma presenting as a localized mass in the renal sinus of a 66-year-old man. The chief clinical and radiologic differential diagnostic considerations in this case included a malignant renal tumor arising in the hilum. The patient was being investigated for recurrent urinary tract infections and vague abdominal pains. Histologically, the lesion showed features characteristic of a myelolipoma. There was also marked chronic inflammation in and around the mass. The uneventful follow-up of 62 months is in keeping with the benign nature of this lesion. This report expands the possibilities of the differential diagnoses of renal hilar neoplasms, particularly in view of the increased use of imaging techniques that are bound to detect many incidental lesions in this region.