Muscle Metastasis of Clear Cell Renal Cell Carcinoma Representing as Forearm Mass:A Case Report / 대한피부과학회지

ABSTRACT

Cutaneous metastases from renal cell carcinoma (RCC) present as rapidly growing erythematous or purple-round nodules. An 88-year-old male presented with a solitary, deep-seated firm mass on his left forearm that had persisted for 3 years. Ultrasonography revealed an hypervascular mass with rich vessels. Magnetic resonance imaging revealed a 1.6×1.6×3.3 cm sized, high T2-weighted signal intensity mass at brachioradialis muscle. Histopathologic examination revealed cells with atypical, pleomorphic, oval to spindle-shaped nuclei, and clear cytoplasm with an alveolar pattern within an unencapsulated, lobulated mass. Immunohistochemical analysis showed that the tumor cells were positive for PAX8, CD10, epithelial membrane antigen, and vimentin. Ultrasonography of the urinary tract revealed a lesion suspected to be RCC, which was thought to be the primary tumor. As our patient showed peculiar clinical symptoms and the primary tumor was later diagnosed as a metastatic lesion inversely, we report a rare case of metastatic RCC with an intramuscular mass on the forearm.