An immunohistochemical study of the origin of the solid strand in syringoma, using carcinoembryonic antigen, epithelial membrane antigen, and cytokeratin 5

Background  Although much research has been conducted into the origin of syringoma, the histogenesis and differentiation of it remains controversial. The published studies examined various antibodies, and our study is an additional immunohistochemical work-up. Objective  We attempted to identify the cell that acts as the precise origin of a syringoma, based on a comparative analysis of carcinoembryonic antigen (CEA), epithelial membrane antigen (EMA), and cytokeratin (CK) 5 through immunohistochemical staining in the solid strand of basophilic epithelial cells of syringoma. Methods  A total of 31 patients with biopsy-confirmed syringoma were included in this study. Each sample was analyzed with antibodies to CEA, EMA, and CK5. These markers were indicating each part of the normal sweat gland structure: CEA stains the luminal surface of sweat ductal structures; EMA stains the peripheral cells of normal dermal ducts and the intraepidermal duct; CK5 stains the outer cells of the dermal duct and lower intraepidermal duct but does not stain the intraepidermal duct located in the upper epidermis. Results  We were able to confirm that the solid strands stained for EMA and CK5, as did the outer cells of the ductal structure. However, the solid strands did not stain with CEA. Conclusions  The results indicated that solid strands observed in syringomas originate from the outer cells of the two layers of cells that compose the lower epidermal duct or the transitional portion between the intraepidermal duct and dermal duct in the normal eccrine or apocrine structure. Thus, we surmise that a syringoma is developed by the proliferation of these cells.