Hyaline cell-rich chondroid syringoma: epithelial nature of the hyaline cells

We report a case of hyaline cell-rich chondroid syringoma arising in the skin on the left side of the neck. The tumor was composed exclusively of hyaline cells arranged in a predominantly thick trabecular pattern. Ductal structures of various sizes in the tumor were composed of eosinophilic cuboidal cells showing transition to hyaline cells. Immunohistochemically, the hyaline cells were positive for cytokeratin, S-100, and vimentin, although the best marker for myoepithelial differentiation, alpha-smooth muscle actin, was negative. As is the case with plasmacytoid monomorphic adenomas of the salivary gland and some reported cases of hyaline cell-rich chondroid syringoma, hyaline cells in the present tumor similarly lacked any evidence of myoepithelial differentiation. These immunohistochemical findings reveal that the hyaline cells in the present tumor were epithelial.