Rare Skeletal Muscle Metastasis After Radical Nephrectomy for Renal Cell Carcinoma: Evaluation of Two Cases

Renal cell carcinomas (RCCs) commonly cause metastases to the lung, liver, bone and brain but rarely to the skeletal muscles. We describe solitary large masses located in the gluteus maximus and medius muscles in two patients who had a history of RCC treated with nephrectomy. Metastatic RCC must be distinguished from benign primary soft tissue tumors because it requires aggressive surgical resection. An open incisional biopsy revealed RCC metastasis. Both patients underwent complete resection of the large mass with additional local radiotherapy and immunochemotherapy. This incalculable course of RCC suggests the need to perform a thorough postoperative follow-up of such patients.