Cutaneous sclerosing perineurioma of the digits: an uncommon soft-tissue neoplasm. Report of two cases with immunohistochemical analysis

Background:  Cutaneous sclerosing perineurioma is a recently characterized, uncommon tumor composed of perineurial cells, which exhibits immunoreactivity for epithelial membrane antigen (EMA). These lesions occur preferentially in children and young adults and usually develop as dermal or subcutaneous nodules in the hands or palms. Methods:  We report two cases of cutaneous sclerosing perineurioma in young patients without stigmata of neurofibromatosis. Histologically, these lesions were well-circumscribed masses and were characterized by a variable number of epithelioid and spindle cells with wavy nuclei end elongated cytoplasmic processes embedded in a dense collagen stroma. Results:  These cells showed focal whorling formation, demonstrated robust immunoreactivity for EMA and CD99, and were uniformly negative for S-100 protein, actin (HHF-35), CD34, cytokeratin AE1-3, and CD57. Conclusion:  We comment on the differential diagnosis of fibrous cutaneous lesions based on immunohistochemistry.