Baker's Cyst

Baker’s cyst (Popliteal cyst) is among the common conditions that occur in the knee region. This cyst usually results due to some problem in the knee joint (such as osteoarthritis or a meniscus tear) that results in excessive synovial fluid production leading to swelling of popliteal bursa which manifests as baker’s cyst. Text Reference and Image Source: https://orthoinfo.aaos.org/en/diseases--conditions/bakers-cyst-popliteal-cyst/