Soft‐tissue perineurioma in a 20‐year‐old patient with neurofibromatosis type 1 (NF1): report of a case and review of the literature

Abstract

Perineurioma is a rare benign soft-tissue tumor composed of cells showing differentiation toward the perineurial cells of the nerve sheath. Although mutations in the neurofibromatosis 2 (NF2) gene have been documented in this tumor, there is no known association between perineuriomas and type 1 or 2 NF. This is the first report of a case of soft-tissue perineurioma occurring in a patient with NF1. Histopathologic examination revealed a 2.0-cm well-circumscribed, spindle-cell neoplasm with slender, elongated, bipolar, wavy cytoplasmic processes and wavy, elongated nuclei in a hyalinized stroma with focal myxoid areas. The architecture was composed predominantly of short fascicles with areas exhibiting a storiform pattern. Immunohistochemistry showed positive labeling for epithelial membrane antigen (EMA) but no staining for S-100 and smooth muscle actin (SMA). This case illustrates that perineurioma can occur in association with NF1. Perineuriomas can be confused with other spindle-cell neoplasms, and relevant features and immunohistochemistry of these lesions are outlined. The patient has not had a recurrence with limited follow-up.