Primary osteoma cutis. Clinical, morphological, and ultrastructural study.

Primary osteoma cutis arises in the deeper dermis for no apparent reason and presents as mature, lamellar, and osteonic bone; secondary cutaneous osteomas are correlated with inflammatory processes, scars, or dysembryoplasia and are always composed of osteoid. Ultrastructural findings of primary cutaneous osteomas have not been reported to date. Light and electron microscopic findings of a case of primary osteoma cutis are described: mineralized areas may be divided into macrocalcification and microcalcification. Macrocalcification consists of lamellar bone