THE USE OF ANTIDESMOGLEIN STAINS IN MOHS MICROGRAPHIC SURGERY - A POTENTIAL AID FOR THE DIFFERENTIATION OF BASAL-CELL CARCINOMA FROM HORIZONTAL SECTIONS OF THE HAIR FOLLICLE AND FOLLICULOCENTRIC BASALOID PROLIFERATION

BACKGROUND. Histopathologic differentiation between benign and maligna nt tissue is of utmost importance for the Mohs surgeon. Folliculocentr ic basaloid proliferation (FBP) shares many histologic features with b asal cell carcinoma (BCC). It is most commonly associated with tumors of areas with abundant hair follicles such as nasal and perinasal skin . Residual BCC incorrectly identified as a horizontally sectioned hair follicle undoubtedly increases the risk of tumor recurrence. Excision of additional layers of normal tissue to remove ''funny looking folli cles'' may have profound impacts on tissue conservation preservation o f function; and cosmesis. Electron microscope studies of BCC revealed a significant reduction of desmosomes compared with normal basal cells and hair follicle keratinocytes. OBJECTIVE. This study has assessed t he potential of rapid staining with monoclonal antidesmoglein antibody (33-3D) to discriminate between BCC, horizontally sectioned hair foll icles, and FBP. METHODS. A rapid immunoperoxidase technique with 33-3D antidesmoglein antibody was performed on Mohs frozen sections. We sel ected 28 patients with BCC of nasal and perinasal locations where hist ologic discrimination between residual tumor and tumor-free margins wi th FBP or horizontally sectioned hair follicle was equivocal. RESULTS. Fourteen sections disclosed the preservation of desmoglein marker del ineating the cell membranes (''perimembranous'' pattern) consistent wi th normal hair follicles. The sections were identified as tumor-free a nd no additional stages were performed. The remaining four sections re vealed absent perimembranous pattern but presence of diffuse cytoplasm ic staining. These were diagnosed as positive for residual BCC requiri ng the excision of another layer of tissue to obtain tumor-free margin s. A follow-up period ranging from 6 to 24 months revealed no instance of recurrent disease. CONCLUSION. Rapid detection of desmoglein with 33-3D antibody is a promising tool for discrimination between residual BCC and FBP or horizontally sectioned hair follicles. It may enhance the sensitivity of Mohs surgery by disclosing the hidden foci of BCC, thus preventing tumor recurrence and unnecessary excision of normal ti ssue. (C) 1997 by the American Society for Dermatologic Surgery, Inc.