Cutaneous malignant mixed tumor. Report of a case and review of the literature

We describe an unusual malignant cutaneous neoplasm having a biphasic growth pattern and apparently arising in a mixed tumor. A lymph node metastasis was similar histologically to the primary lesion, exhibiting both carcinomatous differentiation and areas that appeared sarcomatous. Immunohistochemical stains showed selective staining for high molecular weight keratin in carcinomatous areas and for vimentin in areas having a sarcomatous appearance. The literature of cutaneous malignant mixed tumor is reviewed and possible explanations for the unusual morphology and immunohistochemical staining pattern are discussed.