Breast metastasis in an adult woman with alveolar rhabdomyosarcoma of the ethmoid sinus.

A new breast mass was identified in an adult woman undergoing treatment for a known ethmoid sinus alveolar rhabdomyosarcoma. Histopathological evaluation revealed alveolar rhabdomyosarcoma metastatic to the breast. Alveolar rhabdomyosarcoma, primarily described in adolescents and especially rare in adults, can uncommonly metastasize to the breast.