Benign Schwannoma With Perineurioma-Like Areas: A Clinicopathologic Study of 11 Cases

appearance that uniformly exhibit areas that are positive for S-100-protein and negative for epithelial membrane antigen (EMA) intermixed with S-100-protein−/EMA+ areas identical to retiform (reticular) perineurioma, the consultation lesion under discus-sion was not acrally located, and the perineurioma-like areas identified on hematoxylin and eosin-stained sections were EMA − on repeated testing, raising the question of how to classify this lesion. We had previously rarely encountered similar tumors with hybrid schwannoma-perineurioma appear-ance lacking EMA reactivity in the perineurioma-like areas, thus defying classification according to present schemes. In our experience, such tumors are very rare and they have not hitherto been studie