IS case 488: Osteopetrosis complicated by rickets
Imaging Sciences URMC 2010
Publication Date: 2010-08-30
History
Patient is a 10-month-old male with a history of failure to thrive. Upper gastrografin enema was performed and an incidental finding of unusual looking bones was made.
Findings
Radiographs showed features of both osteopetrosis and rickets. Osteopetrosis findings included bone within bone appearance, sclerosis of bone, sclerosis of vertebral bodies, sandwich-like appearance of vertebral bodies, and thickening of the skull base. Rickets findings included diffuse metaphyseal cupping and fraying, diffuse periosteal reaction, prominence of the costochondral junctions, and increased distance between the metaphysis and epiphysis in multiple areas.
Diagnosis
Discussion
Osteopetrosis is an unusual inherited disorder of bone formed by endochondral ossification. The osteoclasts are defective in resorbing and remodeling bone, resulting in dense bony sclerosis. Because of osteoclast dysfunction, there is an excessive accumulation of calcified cartilage matrix in the medullary portion of the flat bones, long and short tubular bones, as well as the vertebrae. Two major variants of osteopetrosis have been described. The infantile autosomal-recessive form is frequently fatal without bone marrow transplantation because of severe anemia from bone packing in the marrow cavity. The benign autosomal-dominant adult form usually gives a long life span. Radiographic findings include bone within bone appearance, sclerosis of bone, sclerosis of vertebral bodies, sandwich like appearance of vertebral bodies, thickening of skull base.
Osteopetrosis can be complicated by rickets. Despite having a positive total balance of calcium, these patients are susceptible to rickets because the dysfunctional osteoclasts cannot maintain a normal calcium-phosphorus balance. The skeleton sequesters more than 99% of the calcium. This is important to recognize because the main therapy for infantile osteopetrosis is bone marrow transplantation, which is rendered ineffective in reversing the disorder in the presence of rickets. Radiographic findings of rickets includes diffuse metaphyseal cupping and fraying, diffuse periosteal reaction, prominence of the costochondral junctions, and increased distance between the metaphysis and epiphysis in multiple areas.
References
- Donnelly LF. Pediatric Imaging: The Fundamentals. Philadelphia: Saunders, 2009.
- Donnelly LF, Johnson JF 3rd, Benzing G. Infantile osteopetrosis complicated by rickets. AJR Am J Roentgenol. 1995 Apr;164(4):968-70. PMID: 7726058
- Greenspan A. Orthopedic Imaging: A Practical Approach, 4th ed. Philadelphia: Lippincott Williams & Wilkins, 2004.
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