Extra-acral cutaneous sclerosing perineurioma with CD34 fingerprint pattern.

Sclerosing perineuroma is a variant of extraneural perineurioma that, as a rule, occurs in acral sites. However, it has also been occasionally reported in non-acral regions. Recently, CD34 expression in a pattern reminiscent of the human fingerprint has been observed in a subset of perineuriomas, but this immunohistochemical finding has not been documented in non-acral sclerosing perineuriomas. We report a case of sclerosing perineurioma presenting CD34 expression in a fingerprint-like pattern on the skin of the neck (a previously unreported site for this neoplasm) of a 56-year-old man. In addition, alpha smooth-muscle actin showed a similar pattern of expression, suggesting that the cell population implicated in the remarkable immunolabeling is most probably fibroblastic/myofibroblastic. Other immunohistochemical findings included epithelial membrane antigen and claudin1-positive lesional cells, and the absence of S100, glucose transporter protein 1, MUC4 and desmin.