[Cutaneous perineurioma. Clinical and histological findings and differential diagnosis].

Perineuriomas, composed almost exclusively of EMA (epithelial membrane antigen) positive cells, represent a rare and distinct entity in the spectrum of nerve sheath tumours. At present three subtypes, including intraneural and extraneural perineurioma as well as sclerosing perineurioma, can be distinguished; atypical and malignant perineuriomas are extremely uncommon. We analysed the clinicopathological and immunohistochemcial features of 13 cases of cutaneous perineurioma. The neoplasms arose in adult patients (age range from 18 to 71 years) and were seen on the hand (six cases), the thigh (three cases), the lower leg (two cases), the forearm (one case) and in perinasal location (one case). Morphologically, seven neoplasms showed features of dermatofibroma-like perineurioma, four lesions were consistent with sclerosing perineurioma, one cellular lesion resembled a solitary fibrous tumour, and one case was diagnosed as atypical/malignant cutaneous perineurioma; no local recurrences or tumour progression has been reported so far. The differential diagnosis of various variants of cutaneous perineurioma from other mesenchymal lesions as well as melanocytic and epithelial neoplasms is discussed.