Secondary Cutaneous Ossification in Keloids of the Lower Abdomen: A Report of Two Cases

Cutaneous ossification is a rare benign dermatological condition in which bone forms in the dermis or subcutaneous tissue. It is classified as primary when it emerges without a pre-existing condition and secondary when it is associated with an underlying condition such as trauma, scars, inflammation, or neoplastic disease. The secondary form accounts for most cases of cutaneous ossification. The pathogenesis of cutaneous ossification is not clear. Keloids are benign fibroproliferative skin disorders characterized by chronic inflammation. Their pathogenesis is also not fully understood. We report two cases of postoperative secondary ossification in lower abdominal keloids and review the literature on secondary ossification of the skin. We speculate that severe chronic inflammation in keloids drives osteoblastic transformation of mesenchymal stem cells, endothelial cells, or fibroblasts in the keloids.