Nerve sheath myxoma: an immunohistochemical study of a case.

An 18-year-old Japanese male presented with a normal-skin-colored, dome-shaped, slightly tender tumor on his left palm. Histopathologically, the tumor consisted of distinct lobules, which were separated by fibrous connective tissue. Each lobule was composed of spindle or round cells within a myxoid matrix, pathognomonic of nerve sheath myxoma. The mucinous material was positively stained by Alcian blue (pH 2.5) and toluidine blue (pH 4.0). Immunohistochemically, the majority of spindle cells were positive for S-100 protein (beta-subunit) and neuron-specific enolase. Our findings lend further support to the hypothesis that nerve sheath myxoma is derived from Schwann cells.