A Case Report of Bilateral Lipoma Arborescens: An Unusual Consideration for Knee Pain.

Introduction: Lipoma arborescens (LAs) is a benign, intra-articular proliferation of fat cells in villous projections, creating a tree-like pattern on magnetic resonance imaging (MRI). The suprapatellar pouch is usually affected, and symptoms are typically gradual in nature, and patients may report painless swelling of the knee. Only ten cases of bilateral LA have been reported in the literature so far. Early recognition of this disease process and treatment may help to prevent prolonged symptoms and delays in care. Case Report: A 49-year-old female with bilateral knee pain and intermittent swelling for over 20 years presented to our clinic with complaints of bilateral knee pain and swelling. She had previous steroid injection but no relief. After MRI was obtained concerning for LA, a surgical discussion was had with the patient about arthroscopic removal. She elected to proceed with surgery and underwent arthroscopic debridement of both knees. At her follow-up at 6 months for the right knee and 2 months for the left knee, she had a significant improvement in pain and quality of life. Conclusion: LA of the knee is a rare condition, particularly bilateral, and in this patient, the diagnosis was missed for many years, and her definitive treatment was delayed. In her case, arthroscopic debridement of her bilateral LA proved to be a viable treatment option which significantly improved the patient's quality of life and function.