Myoepitheliomas of the skin and soft tissues - Report of 12 cases

We describe 12 cutaneous and soft tissue myoepitheliomas, most of them in e lderly patients. Morphologically the cutaneous and soft tissue myoepithelio mas revealed the same spectrum as their salivary gland counterparts. They w ere composed of a mixture of spindle, epithelioid and clear myoepithelial c ells. Immunohistochemically they were positive to keratins and S-100 protei n and reacted inconsistently with antibodies to smooth muscle actin. Morpho logically they lacked any folliculo-sebaceous or apocrine differentiation. We believe that they are related to the eccrine type of cutaneous mixed rum ours. Most cases had a benign behaviour, but 1 tumour metastasized, and the patient died of the tumour. Myoepitheliomas of soft tissues should be dist inguished from other neoplasms with epithelial differentiation and from oss ifying fibromyxoid tumour of soft parts, parachordoma and extraskeletal myx oid chondrosarcoma.