Tenosynovial lipoma arborescens of the ankle in a child.

Lipoma arborescens is a rare entity of the synovium and frequently occurs in the joints. Lipoma arborescens involving the synovial sheaths of the tendons is exceedingly rare. We report a case of a 12-year-old girl with lipoma arborescence affecting the synovial sheaths of the peroneal, posterior tibialis, and flexor tendons. Identification of the typical features of fat tissues in the proliferative synovium on MRI may help in making a correct diagnosis. The clinical presentation and MRI findings are described, and the entity is briefly reviewed.