Malignant infantile osteopetrosis
A rare infantile osteosclerosing dysplasia with poor prognosis.
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Malignant infantile osteopetrosis is a rare osteosclerosing skeletal dysplasia that presents in infancy. It is characterized by generalized hyperostosis with a predilection for the medullary portion of bone, leading to serious hematologic and neurologic complications. The prognosis is extremely poor in untreated cases, and plain radiography provides key diagnostic information.
Presentation
Hematologic manifestations from bone marrow suppression and pancytopenia are major sources of morbidity and mortality. Extramedullary hematopoiesis can cause liver and spleen dysfunction. Cranial nerve dysfunction and neurologic complications are common, along with macrocephaly from skull expansion. Linear growth retardation, delayed motor milestones, and poor dentition may also occur.
Diagnosis
Radiographs show a generalized increase in bone density of the medullary portion with relative cortical sparing, uniformly involving axial and appendicular skeleton. Hallmarks include loss of medullary-cortical differentiation, a bone-within-bone appearance in the spine (sandwich vertebra) and pelvis, and Erlenmeyer flask deformity of distal femoral and proximal humeral metaphyses. Alternating radiolucent femoral metaphyseal bands and pathologic fractures are seen. Differential diagnosis includes other osteosclerosing dysplasias such as neuropathic infantile osteopetrosis, infantile osteopetrosis with renal tubular acidosis, and autosomal dominant osteopetrosis.
Treatment
Hematopoietic stem cell transplantation is the only effective treatment, providing long-term disease-free periods for a significant percentage of patients. It can impact both hematologic and skeletal abnormalities, with radiographs demonstrating bone remodeling and recanalization of medullary canals within one year. Primary graft failure can prove fatal.
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Sources
Compiled from Wikipedia and the sources listed below. Text from Wikipedia is available under CC BY-SA 4.0; this entry is adapted from it.
- Wikipedia: Malignant infantile osteopetrosis (CC BY-SA 4.0).
- Word definitions: the , each quoted from its Wikipedia article.
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