Lipoma arborescens of the suprapatellar bursa and extensor digitorum longus tendon sheath: report of 2 cases

Abstract

Objective: Lipoma arborescens (diffuse articular lipomatosis) is a rare intra-articular lesion consisting of subsynovial villous proliferation of mature fat cells. The usual clinical presentation is painless swelling. The aim of this series was to emphasize the importance of gray scale and color Doppler sonography through the investigation of chronic joint swelling.

Methods: Lipoma arborescens of the knee and extensor digitorum longus tendon sheath at the ankle region are described. The latter is extremely rare. We examined 2 patients with sonography before using cross-sectional modalities.

Results: Gray scale sonography revealed hyperechoic irregular villous and frondlike projections within prominent joint effusion. A wavelike motion of the projections was shown by dynamic compression and manipulation of the effusion. We observed moderate vascularity on color Doppler sonography. Spectral analysis revealed a low-resistance arterial waveform.

Conclusions: Gray scale sonography is a useful diagnostic modality that can be performed to evaluate chronic joint swelling before the use of cross-sectional and more expensive modalities.