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Osteopetrosis — MFDS Part 1 MCQ

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HardOral PathologyOsteopetrosisMFDS Part 1

A 9-year-old with multiple unerupted permanent teeth is investigated for pallor, easy bruising, recurrent low-trauma fractures and slowly progressive visual impairment. Blood tests show anaemia and thrombocytopenia. Panoramic and skeletal radiographs demonstrate diffuse, symmetrical skeletal sclerosis with marked narrowing of the medullary cavities. Despite the increased radiodensity, previous fractures have healed poorly. Which diagnosis best explains the combined dental, haematological, neurological and radiographic findings?

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Correct answer: D — Osteopetrosis

The diagnosis is **osteopetrosis**. Defective osteoclast formation or function prevents normal bone resorption, producing diffuse radiographic sclerosis but mechanically abnormal, brittle bone. Failure to remodel alveolar bone impedes creation of the eruption pathway, causing unerupted teeth. Obliteration of marrow spaces explains anaemia and thrombocytopenia, while narrowing of cranial nerve canals may cause visual impairment. Osteogenesis imperfecta also causes fragility fractures but usually produces reduced bone mass and may cause dentinogenesis imperfecta. Paget disease is principally an adult disorder with disorganised, often expanded bone. Fibrous dysplasia produces localised or regional ground-glass expansion rather than generalised sclerosis and marrow failure. Osteomalacia is defective mineralisation and causes reduced radiodensity.

Reference: Funck-Brentano T, et al. Osteopetrosis and related osteoclast disorders in adults: A review and knowledge gaps on behalf of the European Calcified Tissue Society and ERN BOND. European Journal of Medical Genetics. 2024;69:104936. https://pubmed.ncbi.nlm.nih.gov/38593953/