Scrape cytology of pemphigus vulgaris of the nipple, a mimicker of Paget's disease.

A case of histologically and immunocytochemically confirmed pemphigus vulgaris of the nipple examined by scrape cytology is reported. The scrape cytology showed isolated and somewhat loosely clustered cells with basophilic cytoplasm and vesicular hyperchromatic nuclei dysplaying prominent nucleoli, suggesting Paget's disease of the nipple. However, histological examination of the resected tissue together with the direct immunofluorescence technique for demonstration of in vivo-bound immunoglobulin to epithelium confirmed the diagnosis of pemphigus vulgaris. The use of an immunoperoxidase stain for IgG on the Papaniolaou-destained smear also gave a positive reaction on the cell membranes and provided a precise cellular diagnosis of the lesions. Cytodiagnostic pitfalls of these rare breast lesions are discussed, as well as the diagnostic value of immunocytochemistry.