Presentation
Motorcycle accident. Midshaft deformity of the lower leg.
Patient Data
Eccentrical metaphyseal multiloculated lucent lesion with a sclerotic rim.
There is no periosteal reaction, the sclerotic rim touches the cortical without breaching it.
These characteristics are highly suggestive of a non-ossifying fibroma.
Case Discussion
Non-ossifying fibromas are common non-neoplastic bone lesions, usually seen in children and adolescents.
They have the typical appearance of a multiloculated lucent lesion with a sclerotic rim. They are commonly located eccentrically in the metaphyses of long bones. Lesions with this appearance but <3 cm used to be referred to as fibrous cortical defects. However, this terminology is no longer recommended by the WHO.
Due to their characteristic appearance and outcome, most of them require neither treatment nor biopsy. Because of this, non-ossifying fibromas are one of the "don't touch" lesions.
These lesions are mostly asymptomatic and found incidentally, which happened in this case. The patient had a tibia shaft fracture and the non-ossifying fibroma was an incidental finding of the knee radiographs.