Type II collagen in mixed tumors of the skin. An immunohistochemical study and new speculations concerning histogenesis.

We studied 11 cases of mixed tumor of the skin with a polyclonal antibody against human type II collagen. Two of the cases were of the eccrine type, six were apocine, and three were malignant. In all of the benign cases of mixed tumor and in some of the malignant type, "chondroid" and mucinous portions stained. The clearly epithelial portions of the tumor stained as well, and staining was most intense in the eccrine types and least intense in the malignant types. The positive staining in mixed tumors may help elucidate the histogenesis of these unusual tumors as well as help differentiate among the various subtypes.