Presentation
Anterior pain of the left knee.
Patient Data
Small well-defined, smooth-walled lobulated cystic mass within the lateral aspect of the Hoffa's fat pad. It displays a low signal on T1 and high signal on PD fat sat. Normal appearance of the adjacent anterior horn of the lateral meniscus.
The cruciate and collateral ligaments are intact.
Mild joint effusion.
A small tibial subchondral cyst is noted.
Case Discussion
Hoffa fat pad ganglion cysts are considered as intra-articular ganglion cysts. They are the most common mass-like lesions within the Hoffa fat pad and represent one type of many cyst-like lesions around the knee.
The main differential diagnosis is the parameniscal cyst which is associated with a meniscal tear in the vast majority of cases.