Sclerosing perineuriomas affecting bilateral hands

Sclerosing perineurioma is a rare, recently described variant of perineurioma that tends to affect the fingers and palms of adolescents or young adults. The process typically presents as a painless, well-circumscribed, unencapsulated nodule involving subcutis or reticular dermis. To our knowledge, all of the previously reported sclerosing perineuriomas were solitary. Hence, we report a 16-year-old boy, without stigmata of neurofibromatosis, who developed one sclerosing perineurioma in the right palm and another on the left index finger. Microscopically, tumours at both sites revealed small epithelioid and plump spindle cells with trabecular, whorled, or Indian file growth pattern enmeshed within extensively hyalinizing stroma. Immunohistochemically, the tumour cells showed strong reactivity for E, MA but negative staining for S-100 and neurofilament. Ultrastructually, the tumour cells in both lesions exhibited features of perineurial cells, including discontinuous external basal lamina, occasional pinocytotic vesicles, and encirclement of abundant collagen fibrils by the interdigitating cytoplasmic processes. This case confirms the fact that sclerosing perineurioma is not always solitary.