Findings: These are two views of the right distal tibia in a skeletally mature patient demonstrating an eccentric, cortically based, well-marginated lytic lesion with multiple internal septations. There is no evidence of periostitis.

Diagnosis: Fibroxanthoma.

Discussion: Fibroxanthoma (or benign fibrous histiocytoma) is similar to nonossifying fibroma. Its existence as a separate lesion from nonossifying fibroma is debated. Nearly all fibroxanthomas occur in patients older than 20 years of age. Many patients present with pain. In contraindication to nonossifying fibroma, fibroxanthoma is most common in the diaphysis or epiphysis of long bones as well as the sacrum and ilium. In addition, nonossifying fibroma nearly always manifests in patients under 20 years of age. The radiographic findings of fibroxanthoma are variable and generally nondiagnostic. They may resemble nonossifying fibroma, fibrous dysplasia, enchondroma, or eosinophilic granuloma. There have been reported cases of aggressive lesions with local spread and dissemination.

Reference:
Resnick D. Diagnosis of Bone and Joint Disorders, 2nd Edition.
W. B. Saunders; 1988:3756-3757.

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