Cutaneous Bone Formation Associated With Melanocytic Nevus

Cutaneous bone formation is an uncommon lesion of the skin. It may be primary or secondary. Secondary lesions are mostly associated with melanocytic nevi. Although many different theories have been proposed to explain the etiology, extraskeletal bone formation is complex and poorly understood phenomenon.Here the authors report a series of melanocytic nevi with cutaneous bone formation and the authors described morphologic and clinicopathologic features such as age, sex, location, focus number and size of the lesion.

Through a single center, this retrospective study presents total number of 20 patients with melanocytic nevus with or without osseous metaplasia. Histologic and clinicopathologic features such as age, sex, location, focus, and size of lesion were compared.

Lesions were identified in 10 female patients. All of the cases were seen in the head and neck region such as face, forehead, eyebrow, lip, and neck and most of them were solitary. The nevi were usually associated with the single focus of ossification. Most of patients (50%) had acne symptoms and treatment anamnesis. Granulomatous dermal inflammation was seen in 2 patients. There was no difference in nevus morphology and the size of the nevi between the osteonevi and the other types of nevi.

In conclusion, this study revealed that although it is rare it has distinctive features such as female patients, face location, and acne anamnesis. Therefore it may be speculated that the osteogenic factors may be involved with inflammatory-induced metaplastic ossification and tend to be related female sex.