Lipoma Arborescens in the Knee Joint

Abstract

Lipoma arborescens (LA) is an unusual and benign lesion found in joints, where one can see villous lipomatous synovial proliferation, with the knee joint being the commonest site. It typically presents with chronic joint swelling and pain. We report the case of a 32-year-old woman with a history of knee trauma three years ago, who presented with progressive pain and swelling in the left knee. Examination revealed swelling with a boggy consistency over the suprapatellar area. There was no joint line tenderness, and the routine clinical tests did not reveal any abnormality. Magnetic resonance imaging indicated synovial proliferation with frond-like synovial mass in the suprapatellar pouch, lateral aspect. Synovial debridement was planned after, which was then performed arthroscopically. Synovial biopsy histopathological examination confirmed the diagnosis of lipoma arborescens. Postoperatively, the patient recovered uneventfully and was able to pursue daily activities without any hindrance. Lipoma arborescens is a rare condition and should be considered in patients with chronic knee swelling and clinical and radiological features suggestive of florid synovitis. Arthroscopic debridement remains an effective treatment.

Keywords: arthroscopic synovectomy; frond-like synovial mass; knee swelling; lipoma arborescens; rare knee tumor.

Figure 1. MRI images of the pathology

A: axial image, B: sagittal image Arrows indicate the frond-like arborescent synovial mass. MRI: magnetic resonance imaging

Figure 2. Arthroscopic image of the pathology

The arrow indicates frond-like fatty villous synovial proliferations.