- Fluid collection in popliteal fossa that develops over time related to arthritis, trauma, idiopathic
- Communicates w/joint space
- Can rupture spontaneously
- Prior to rupture, usually asymptomatic, sometimes vague discomfort behind knee
- When ruptures, patient notes acute asymmetric lower extremity edema
- Usually no frank pain (mild discomfort)
- Asymmetric edema, raising concern for DVT
- Pre-rupture, sometimes can identify fullness from cyst in popliteal fossa