Lipoma arborescens of knee joint: role of imaging

A 23 year old Asian female presented with swelling of right knee joint for 5 years with history of exacerbations and remissions of symptoms. She was initially diagnosed as a case of suprapatellar bursitis based on clinical and X-ray findings. Further evaluation with higher imaging modalities was pathognomonic of lipoma arborescens. Patient underwent synovectomy and the diagnosis was confirmed histologically. We describe a histologically proven case of lipoma arborescens to highlight the imaging findings on X-ray, Ultrasound and Magnetic resonance imaging with arthroscopic correlation. The unique feature of this case report is multimodality imaging correlation with arthroscopy and histopathology findings. We have highlighted the pathognomonic imaging findings of this rare but benign intra-articular lesion and also discussed the differential diagnosis in detail.