🦴 Chapter 740 · Osteopetrosis & Defective Bone Resorption

Nelson Textbook of Pediatrics 22nd Edition | Osteopetrosis (marble bone disease): increased bone density due to defective osteoclast function. Autosomal recessive (malignant infantile): presents in infancy with macrocephaly, hepatosplenomegaly, pancytopenia, visual/hearing loss, hypocalcemia. Autosomal dominant (benign adult): milder, fractures, osteomyelitis of mandible. Pycnodysostosis: short stature, osteosclerosis, acro-osteolysis, brittle bones. Treatment: HSCT for severe ARO, calcitriol, interferon-gamma.

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πŸ“‹ 30 Clinical Scenarios β€” Osteopetrosis & Defective Bone Resorption

πŸ“‡ High‑Yield Review Cards

🩺 Clinical Recognition: Osteopetrosis

Select a presentation to review diagnostic clues and management per Nelson Ch 740.

πŸ“‹ Stepwise Management of Osteopetrosis

πŸ”‘ Key Principles β€” Nelson Chapter 740
β€’ Osteopetrosis: Defective osteoclast resorption β†’ increased bone density, but brittle (prone to fractures). Marrow space encroachment β†’ pancytopenia, extramedullary hematopoiesis (hepatosplenomegaly). Cranial nerve foramina narrowing β†’ blindness, deafness.
β€’ ARO (malignant infantile): TCIRG1 (most common), CLCN7, OSTM1. Presents in infancy with macrocephaly, hepatosplenomegaly, anemia, thrombocytopenia, hypocalcemia (with tetany), visual/hearing loss. HSCT only curative (before irreversible neurologic damage).
β€’ ADO (Albers-SchΓΆnberg disease, benign adult): CLCN7 mutations. Fractures, osteomyelitis of mandible, incidental finding on X-ray. Mild course.
β€’ Pycnodysostosis (CTSK): Short stature, osteosclerosis, acro-osteolysis (resorption of distal phalanges), brittle bones, skull anomalies.
β€’ Treatment: HSCT for severe ARO, calcitriol (stimulates osteoclasts), interferon-gamma (modest benefit), supportive care (transfusions, antibiotics).

    ⚑ Reflex Prompts β€” Clinical Decisions

    πŸ“– Summary: Osteopetrosis (Nelson 740)