Unusual Presentation of Synovial Lipomatosis Mimicking As Septic Arthritis of Knee: A Case Report.

Synovial lipomatosis or lipoma arborescens is a very uncommon pseudo-tumorous lesion of the synovium which more commonly affects the knee joint. The most probable cause of this pathological lesion is degenerative articular disorders of the joint and improper fat accumulation. It is characterized by presence of villous proliferation of the synovium and replacement of the sub-synovial tissue by mature adipocytes which is infiltrated by dense chronic inflammatory cells like lymphocytes, plasma cells and eosinophils. This condition is rarely seen in smaller joints. Its aetiology is still unknown. We report a patient who presented with features of septic arthritis which on intraoperative and histopathological assessment showed features of synovial lipomatosis.