Imaging of cysts and bursae about the knee.

Cystic lesions are common around the knee and are often encountered as an incidental finding on routine magnetic resonance imaging examinations. The clinical presentation of cysts and other fluid collections is variable, depending on their size, location, and relationship to adjacent anatomic structures. This article reviews the anatomy, etiology, clinical presentation, and imaging features of commonly occurring cystic lesions around the knee and discusses some of the potential pitfalls that may be encountered in clinical practice.