Progressive osseous heteroplasia is a cutaneous condition characterized by cutaneous or subcutaneous ossification.According to the Progressive Osseous Heteroplasia Association:
Progressive Osseous Heteroplasia (POH) is a rare genetic condition in which the body makes extra bone in locations where bone should not form. Extra bone develops inside skin, subcutaneous tissue (fat tissue beneath the skin), muscles, tendons, and ligaments. [Source: Wikipedia 
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