An 8-year-old male is brought in by his parents for “growing pains.” He has been limping and has difficulty keeping up with other children on the playground secondary to pain in his legs. This has been progressive over the past 6 to 8 months. He is an otherwise healthy child without recent fever, chills, or significant past medical history. X-rays demonstrate a lesion in the anterior tibial cortex associated with some mild bowing of the bone. The lesion has a “soap-bubble” appearance and there are no other lesions seen.
What is the most likely diagnosis?
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Osteosarcoma
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Osteofibrous dysplasia
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Enchondroma
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Nonossifying fibroma
Discussion
The correct answer is (B). Osteofibrous dysplasia is a distinctive intracortical lesion almost always seen in the anterior tibial cortex, most commonly in children <10 years old. These x-rays reveal classic findings of an elongated, diaphyseal, intracortical, bubbly lytic lesion. Expansile remodeling can be seen, but there is no soft-tissue mass.
On histopathologic examination, what differentiates osteofibrous dysplasia from fibrous dysplasia?
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Presence of osteoblastic rimming
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Presence of eosinophils
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Presence of epithelial nests
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Presence of cigar-shaped nuclei
Discussion
The correct answer is (A). At low power, the features of osteofibrous dysplasia are very similar to those of fibrous dysplasia, including spicules of normal appearing bony trabeculae that are sometimes called “alphabet soup.” However, osteofibrous dysplasia has osteoblastic rimming of these immature trabeculae, while fibrous dysplasia lacks this finding. Eosinophils are not predominant in either case. Epithelial nests are seen in adamantinoma, which differentiates osteofibrous dysplasia from this lesion. Cigar-shaped nuclei are associated with certain sarcomas.
If he remains symptomatic, what treatment is indicated?
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Below-knee amputation
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Wide resection with intercalary graft reconstruction and internal fixation
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Curettage and bone grafting
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Radiation therapy
Discussion
The correct answer is (C). Small, asymptomatic lesions may be observed, however, curettage and bone grafting is indicated for symptomatic lesions. A high recurrence rate has been reported with bone grafting, especially in younger children.
Objectives: Did you learn...?
Clinical and radiographic figures of adamantinoma and osteofibrous dysplasia?
