一位63歲之男性病患因偶然在腹部超音波下發現一右側後腹腔腫瘤而入內科病房做進一步的評估和檢查，經過完整之生化檢驗和腹部電腦斷層檢查之後，一個位於右側腎上方包含脂肪成分的腫瘤被發現，它的大小有7.1x6.6公分。在右側腎上腺腫瘤的診斷下，病人轉入泌尿科接受右側腎上腺腫瘤切除手術，並在術後經病理科診斷為腎上腺之骨髓脂肪瘤。我們報告這一不常見之病例，並做文獻回顧和討論。

A 63-year-old man was admitted to the ward of Internal Medicine Department due to an incidentally found right retroperitoneal tumor under abdominal sonography without any specific discomforts. After further laboratory biochemical investigation and abdominal computed tomography, a right suprarenal mass with fat component density and 7.1x6.6cm in size was detected. So he was transferred to Urology Department for tumor excision under the impression of right adrenal tumor. A final diagnosis of adrenal myelolipoma was confirmed by histopathological studies. This unusual case is reported with a review of the literature.