Fibrous dysplasia


The imaging features are those of a low aggressive lesion, and differentials would include enchondroma and fibrous dysplasia. 

The lesion was biopsied: Sections show three pieces of tissue comprised of immature woven bone with broad osteoid seams around central calcified areas, surrounded by fibrous tissue with a few osteoclasts and scattered small vessels. There is no inflammation or atypia. No cartilage is present. There is no evidence of malignancy.

DIAGNOSIS: Right little finger proximal phalanx biopsy: Fibrous dysplasia.