Malignant chondroid syringoma: immunohistopathology.

Malignant chondroid syringoma, also called malignant mixed tumor of the skin, is a rare variant of a malignant tumor derived from sweat gland cells. Histologically the tumor is composed of an epithelial and a mesenchymal component. The epithelial structures show glandular differentiation and carcinomatous features. They are embedded in a mucinous stroma with spindle mesenchymal cells and areas of chondroid differentiation. The epithelial cells express cytokeratins. The luminal epithelial cells show binding to the lectin Ulex europaeus; intraluminal cells are carcinoembryonic antigen positive. The stromal cells are cytokeratin negative and sporadically positive for vimentin. Chondroid areas are S-100 protein and vimentin positive. No labeling for actin is seen.