Extra-acral cutaneous/soft tissue sclerosing perineurioma: an under-recognized entity in the differential of CD34-positive cutaneous neoplasms

Methods: Skin biopsy specimens from three patients were evaluated for cytomorphology and degree of associated sclerosis, which was classified as either focal or diffuse. Immunohistochemical expression of epithelial membrane antigen (EMA), CD34 and S-100 was also assessed to facilitate further classification. Results: Histopathologically, the tumors showed both focal and diffuse sclerosis, and lesional cells were generally spindled in shape. Immunohistochemical staining showed diffuse positivity for CD34 and focal or diffuse positivity for EMA. The cells uniformly lacked expression of S-100 protein. Conclusions: Sclerosing perineuriomas can occur in extra-acral locations and should be considered in the differential of EMA-positive cutaneous spindle-cell proliferations. It is also important to recognize that perineuriomas can express CD34 and should be considered in the differential diagnosis of CD34-positive cutaneous neoplasms. Fox M, Gleason BC, Thomas AB, Victor TA, Cibull TC. Extra-acral cutaneous/soft tissue sclerosing perineurioma: an under-recognized entity in the differential of CD34-positive cutaneous neoplasms.