Basal cell carcinosarcoma of the eyelid with osteosarcomatous transformation

A carcinosarcoma is a neoplasm with malignant epithelial and mesenchymal components. It is thought to arise by mesenchymal transformation of the epithelial elements. The cutaneous form of carcinosarcoma is rare and is associated with sun exposure; most cases arise in the head and neck. The epithelial component may be a basal cell carcinoma, a squamous cell carcinoma, or an adnexal carcinoma. The mesenchymal component may be an osteosarcoma, a pleomorphic undifferentiated sarcoma, or another type of sarcoma. Only a few cases of cutaneous carcinosarcoma have been described in the periocular skin. We present a case of basal cell carcinosarcoma with osteosarcoma and pleomorphic undifferentiated sarcoma arising in the lower eyelid of an elderly man.