悪性腫瘍との鑑別が困難であった腎血管筋脂肪腫

A Case of Renal Angiomyolipoma which was Diffricult to Differentiate from Renal Malignant Tumor

　症例は27歳，女性。主訴は左側腹部痛。当院内科にて左腎腫瘍を指摘され当科を紹介。超音波で左腎に低エコーの充実性腫瘤を認め，CT上左腎に辺縁不整，内部不均一な充実性腫瘍を認めた。MRI上T1,T2強調像ともに低信号で，血管造影ではhypovascular。腎細胞癌や肉腫などを疑い左腎全摘術を施行した。病理組織学的に腎平滑筋肉腫と診断されたが，HMB−45染色陽性を示したため病理部より後日，腎血管筋脂肪腫と訂正された。

A 27-year-old woman was admitted with left flank pail. Laboratory examinations were within normal limits. U showed a hypoechoic left renal tumor. CT confirmed a mass of irregular enhancement. Both Ti and T2 weighted MRI revealed low intensity mass. Selective left renal angiography showed a hypovascular tumor. These findings suggestedrenal cell carcinoma or sarcoma, therefore left nephrectomy was performed. Initial pathological diagnosis was leiomyo-sarcoma. However, after subsequent histologic examina tions, the tumor was positive for HMB-45 staining, the diagnosis was corrected to angiomyolipoma.