SCHWANNOMA WITH SWEAT-DUCT DIFFERENTIATION

We report a schwannoma with well differentiated ducts resembling cutan eous sweat ducts. The tumor presented as a painless mass near the left knee of a 41-year-old female. The mass had been present for many year s. Some increase in size had been noticed over the previous 2 to 3 yr. The bulk of the tumor was composed of spindle cells with the appearan ce of Antoni A and Antoni B tissue. Rare mitotic figures were noted. I n several areas of the tumor, numerous well-differentiated ducts were present. Most resembled normal cutaneous sweat ducts. In some areas, c ystic dilatation of the ducts was present. Focal areas demonstrated po orly formed ducts and single cells with prominent nuclei and ample cyt oplasm. Well formed ducts, poorly formed ducts, and single cells marke d with AE 1/3 (keratin) and epithelial membrane antigen. The spindle c ell proliferation marked for S 100 protein and vimentin. Sweat duct di fferentiation has not been reported previously in either benign or mal ignant schwannoma. Light and electron microscopic features of this tum or are presented.