Osteopetrosis represents a disease of osteoclastic dysfunction with failure of bone resorption. The marrow becomes filled with unresorbed bone (spongiosa), and myeloid elements become depleted. The disease may be autosomal recessive or dominant. The neonatal or "malignant" form tends to be autosomal recessive and presents with severe marrow depletion and intracranial hemorrhage. These patients may live for several decades but at are risk for overwhelming infections.
The more familiar autosomal dominant form may be asymptomatic. The medullary compartment is obliterated by immature, unresorbed bone, giving the appearance of uniform sclerosis. As a result, these patients may present with transverse fractures, as the bones are, in fact, fragile. In the spine, the characteristic "sandwich" vertebra pattern is encountered. In the skull, the paranasal sinuses are poorly pneumatized.
The process of bone marrow replacement and extramedullary hematopoiesis often results in leukemia. Adults may have mild anemia and cranial nerve disorders due to sclerosis at the base of the skull. Dental caries are common.
Bone marrow transplantation has been employed to attempt to treat the infantile form of the disease.
REFERENCES
Wilson CJ, Vellodi A. Autosomal recessive osteopetrosis: diagnosis, management, and outcome. Arch Dis Child. 2000 Nov;83(5):449-52.
Fasth A, Porras O. Human malignant
osteopetrosis: pathophysiology, management and the role of bone marrow
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Pediatr Transplant. 1999;3 Suppl 1:102-7.