Intraarticular Giant Size Angiolipoma of the Knee Causing Lateral Patellar Dislocation

Background: Angiolipomas are benign tumors usually seen in patients during their 2nd and 3rd decades. The subcutaneous region of the trunk, neck and extremities are the places where they generally settle. There is only one case report on angiolipoma in the knee joint that was resected by arthroscopic procedure in the English literature. Case Report: We present a case of a giant-size multilobular non-infiltrating angiolipoma, extending outside of the right knee joint and causing lateral patellar dislocation in a thirteen-year-old boy. A large encapsulated mass with fatty and soft-tissue components on magnetic resonance imaging was suggestive of a liposarcoma. However, the diagnosis after the tru-cut biopsy was angiolipoma. The Quadriceps angle was 25°. Complete resection of the tumoral mass and repair of the medial retinaculum were performed with open surgery. Patellofemoral alignment was provided by transferring the tibial tuberosity medially. One year after the surgery, there was no evidence of recurrence. Conclusion: Intra-articular angiolipomas are rarely seen masses in the knee joint. To our knowledge, this case report is the first to demonstrate that angiolipoma causes patellar dislocation.