P434 : A case of intradermal nevus with osseous metaplasia

Many interesting changes can uncommonly be seen in benign intradermal melanocytic nevi. Among them, cutaneous bone formation is an uncommon phenomenon which may be primary or secondary. Incidental finding of bone formation in intradermal nevus is known as osteo-nevus of Nanta. Very few cases have been reported so far in the literature. A 46-year-old man presented with a 5-year history of asymptomatic nodule on his right malar area of face. On the physical examination, 0.6Ⅹ0.4 cm sized bluish pigmented nodule was seen on the right malar area. The histological examination showed nests of a dense proliferation of benign nevus cells throughout the entire dermis and revealed a benign pigmented intradermal melanocytic nevus. No evidence of dysplasia or malignancy was seen. Interestingly, focal osseous metaplasia and well circumscribed lamellar bone formation were seen in deep dermis, underneath the nevus cell nests. Herein, we present an unusual case of intradermal melanocytic nevus with osseous metaplasia, osteo-nevus of Nanta, in a Korean male patient.