[Is the presence of horny pseudocysts in the histological picture of nevus cell nevi a sign for a benign lesion?].

Among 2203 nevus cell nevi, 1333 cases showed horny pseudocysts in the histological picture (60.5%). In 1234 out of 1674 cases (73.7%) horny pseudocysts occurred in intradermal nevi. In 332 cases of malignant melanoma, horny pseudocysts did not appear at all. We concluded that the horny pseudocyst if a common histological feature in cases of intradermal nevus but is at least extremely rare in malignant melanoma. Therefore the horny pseudocyst may play an important part as a histological guide for a benign lesion in cases of borderline nevus cell nevi with initial signs of malignant transformation.