Osteopetrosis is a rare inherited skeletal disorders characterized by a marked increase in bone density due to defective bone resorption by osteoclasts. Shown in the picture is a 24-year-old white man with infantile form of osteopetrosis. He has mandibular osteomyelitis, and multiple draining fistulae are present on his face. This severe autosomal recessive form is usually diagnosed at birth or in early infancy. Typical findings include a diffusely sclerotic skeleton, bone marrow failure, frequent fractures, cranial nerve compression, and growth impairment. Reference: Brad W. Neville, Douglas D. Damm, Carl M. Allen, Angela C. Chi - Oral and Maxillofacial Pathology-Saunders (2015)