The Evaluation of Lipoma Arborescens with Intermittent Knee Joint Effusion Based on an Analysis of Serum Cytokine Levels and an Immunohistological Examination.

We herein report a 27-year-old woman who presented with recurrent knee pain. Laboratory findings revealed minimal inflammation. Arthrography revealed structures resembling adipose tissues. Magnetic resonance imaging showed a high signal intensity of these structures, leading to the diagnosis of lipoma arborescens (LA). Synovectomy was performed. Pathology revealed adipocyte proliferation and B-cell clusters but no T-cell infiltration. A serum cytokine analysis revealed low levels of interleukin-6 and tumor necrosis factor-α compared with patients with rheumatoid arthritis. The pathogenesis of LA remains unclear, but immunostaining and serum cytokine levels may provide valuable data for future investigations.