Osteomyelitis of the mandible secondary to malignant infantile osteopetrosis in an adult.

Malignant infantile osteopetrosis (MIOP), an autosomal-recessive disorder, is extremely rare, presenting early in life with extreme sclerosis of the skeleton and reduced activity of osteoclasts. It was first described by Albers Schonberg in 1904. Disease manifestations include compensatory extramedullary haematopoiesis at sites such as the liver and spleen, hepatosplenomegaly, anaemia and thrombocytopaenia. Neurological manifestations can also occur due to narrowing of osseous foramina resulting in visual impairment, hearing loss, facial palsy and hydrocephalus. In addition, growth retardation and recurrent infections requiring long-term antibiotic use are common. The incidence of MIOP is 1/2 000 000 and if untreated, then it has a fatal outcome, with the majority of cases occurring within the first 5 years of life. At present, the only potentially curative option is a haematopoietic stem cell transplant. We present a 21-year-old woman, diagnosed with malignant infantile osteopetrosis, due to a mutation in the T-cell immune regulator 1 gene when aged 6 weeks, presenting with chronic osteomyelitis of her left mandible. As malignant infantile osteopetrosis has a high mortality in infancy, we felt it prudent to report this rare case in a patient surviving to adulthood. © BMJ Publishing Group Limited 2019. No commercial re-use. See rights and permissions. Published by BMJ.