Lipoma Arborescens: A rare cause of knee swelling.

Introduction: Lipoma Arborescens is a chronic, slow growing intra articular lesion of benign nature which is commonly seen in the supra patellar region of the knee joint. It is characterised by villous proliferation of the synovium, with the replacement of the subsynovial connective tissue with fat cells. It is not a neoplasm but non-specific reactive response to chronic synovial irritation, due to mechanical or inflammatory insults. We highlight this condition to raise awareness to be kept as a differential diagnosis in knee joint affected by various slow, progressive chronic inflammatory conditions. Case Report: We present case of 51-year female with severe knee swelling since 3 to 4 years with episodes of remission and regression on and off. She was diagnosed with lipoma arborescens after magnetic resonance imaging and confirmed after post operative histology. Conclusion: We in this case study highlight this rare condition with its imaging characteristics and arthroscopic treatment. Keeping in mind that lipoma arborescens though benign in nature and as one of the rare causes for knee swelling, has to be treated to get an optimal outcome.