Bone deposition in the skin is a rare phenomenon. Only 10 cases of multiple primary miliary osteoma cutis in adults have been documented. The mechanism of the pathogenesis of multiple primary miliary osteoma cutis is not yet clear. It may be due to a disordered embryological process with ectopic rests of normal mesenchymal cells that differentiate normally into osteoblasts or that stimulate normal extraskeletal mesenchymal cells to become osteoblasts. Primary osteoma cutis may be considered a true bone hamartomatous formation rather than dermal mineralization. Therapeutic trials with synthetic diphosphonates failed to achieve any improvement.
Gfesser M, Worret W, Hein R, Ring J. Multiple Primary Miliary Osteoma Cutis. Arch Dermatol. 1998;134(5):641-643. doi: