[Epithelioid angiomyolipoma : a case report].

A 63-year-old woman with a right renal tumor diagnosed by ultrasound, consulted our hospital in October 2008. The findings of her physical examination were unremarkable. The results of urinalysis and other routine blood tests were normal. The urinary cytology was negative for malignant cells. Dynamic computed tomography showed a right renal mass (diameter, 7.5 cm), which was enhanced in the early phase and washed out in the late phase. We initially thought that the patient had renal cell carcinoma. Therefore, laparoscopic right nephrectomy was performed in October 2008. The tumor section was found to be encapsulated, and focal hemorrhage and necrosis were observed. Histological examination of the tumor by hematoxylin-eosin staining revealed that it contained polygonal cells, eosinophilic cytoplasm and large nuclei. Immunohistochemical staining of anticytokeratin antibodies AE1/AE3 and CAM5.2 (markers for renal cell carcinoma) was negative. However, immunohistochemical staining of HMB-45, a marker for melanoma, was positive. The patient was finally diagnosed with epithelioid angiomyolipoma. She did not show any evidence of tumor recurrence for 25 months after the surgery.