["Hyaline-cell chondroid syringoma." Morphological, immunohistochemical and ultrastructural study of a case and review of the literature].

Chondroid syringoma represents the cutaneous counterpart of mixed tumor ("pleomorphic adenoma") of salivary glands, therefore it is also termed mixed tumor of the skin. The presence of hyaline cells in mixed tumors of salivary gland is a very well known event. Tumors mainly or exclusively composed of hyaline cells are termed myoepitheliomas of hyaline type, accordingly to their alleged myoepithelial origin. Scanty components of hyaline cells in chondroid syringomas of the skin have also been observed since more than a decade. However chondroid syringomas mainly or exclusively composed of hyaline cells have been reported only very recently. If the hyaline cells of chondroid syringomas are myoepithelial or epithelial in origin is still a matter of debate, we prefer to retain the descriptive label "hyaline cell-rich chondroid syringoma" as originally conceived by JA Ferrero and AG Nascimento the patronimic authors of the entity. A case of hyaline cell-rich chondroid syringoma is reported on in a white male patient aged 64, which occurred on the external ear of 1-year duration. This case was studied immunohistochemically and ultrastructurally. Both immunoprofile which included reactivity for vimentin, low molecular weight cytokeratins, S-100 protein, GFAP (focally), alfa-smooth actin and muscle-specific actin, and ultrastructural features including evidence of intermediate filaments (non-bundling filaments, tonofilaments), desmosomes, and thin filaments of actin type sustain a myoepithelial differentiation for hyaline cells of this tumor and site. The authors also remark the importance of being aware of this new entity during the diagnostic practice for avoiding misinterpretation. A list of condition to be taken into account in differential diagnosis is also given.