Progressive bilateral lipoma arborescens of the knee complicated by juvenile spondyloarthropathy: A case report and review of the literature

Abstract Objectives To report an unusual case of lipoma aborescens (LA) presented in a patient with treatment-responsive juvenile spondyloarthropathy (JSPA) and to summarize the clinical manifestations, therapy and prognosis of LA by literature review. Methods We report an atypical case of a 17-year-old patient with an initial presentation of juvenile spondyloarthropathy, whose inflammatory condition was improved successfully by traditional anti-rheumatic drugs and an anti-TNF alpha agent but developed progressive swelling of bilateral knees. Lipoma arborescens were diagnosed in each knee by synovial biopsy obtained by arthroscopic surgery. Fifty-one cases of LA have been reported and are reviewed in detail. Results Clinically, LA could present as monoarthritis or oligoarthritis. The lateral compartment of the knee is the most common site of involvement. Several cases were reported as a comorbidity of inflammatory diseases, but were not improved by anti-inflammatory therapy. Most patients were diagnosed by classic MRI and biopsy findings. The lesions can be managed by open or arthroscopic surgery, but a minority of the cases may have reoccurrence in the same or opposite joint. Conclusions LA is a very rare lesion of the synovial and bursal tissue with an unknown etiology. It is considered to be a benign proliferation of the synovial fat associated with trauma, degenerative or inflammatory conditions. LA should be considered as a secondary or comorbid condition in inflammatory arthropathies if other joints respond well to intensive therapy and one or more do not.