[Gluteal muscular metastasis from renal pelvic tumor]

We present a case of gluteal muscular metastasis from a renal pelvic tumor. A 57-year-old man had undergone right nephroureterectomy and received 2 courses of adjuvant chemotherapy (MEC: methotrexate, epirubicin, cisplatin) for invasive renal pelvic tumor. Five months after the operation, computed tomography (CT) revealed pulmonary metastasis and right adrenal gland recurrence. He underwent 2 courses of chemotherapy (gemcitabine, paclitaxel). Postchemotherapy-CT scan showed a 2.2 cm mass in the right gluteal muscle. Since the size of the pulmonary metastasis and right adrenal gland recurrence showed no change, the gluteal mass was excised. Pathological diagnosis was metastatic urothelial carcinoma. Adjuvant chemotherapy (TIN: paclitaxel, ifosfamide, nedaplatin) 3 courses were performed, but postchemotherapy-CT scan showed a new 2.4 cm mass in the right gluteal muscle. He received radiation therapy (total 30 Gy) for the new gluteal mass. The common metastatic sites of renal pelvic tumor are lungs, liver, bone, and lymph nodes. Gluteal muscle is an uncommon site of metastasis of urothelial carcinoma. This is the 1st case of gluteal muscle metastasis from renal pelvic tumor in the literature.