Malignant rhabdoid tumor presenting as a hemangioma.

Malignant rhabdoid tumor is a rare and highly aggressive malignancy of unknown etiology. We report a primary cutaneous rhabdoid tumor on the upper back of a newborn. It was initially diagnosed as a hemangioma clinically, and that diagnosis was supported by radiologic studies, including magnetic resonance imaging. However, detailed investigation with light microscopy, immunohistochemistry, and electron microscopy enabled us to make a diagnosis of rhabdoid tumor. This is the seventh reported case of rhabdoid tumor with primary cutaneous involvement.