Malignant Pilomatrixoma over Left Shoulder: A Case Report.

Pilomatrixoma is a benign neoplasm derived from hair follicle matrix cells. Malignant pilomatrixoma is a rare entity. It is still unclear whether malignant pilomatrixoma arise de novo or it is a malignant transformation in an otherwise benign pilomatrix tumor. 50% of the pilomatrixomas cases occur on the head and neck region, on the cheek, preauricular area, eyelids, forehead, scalp, and lateral and posterior neck. Lesions can also occur on the upper and lower extremities and trunk. Pilomatrixomas are more common in children and are seen more frequently in girls. We present a case of left-arm malignant pilomatrixoma in a 14-year-old girl.