Answer: Hoffa’s fat pad ganglion cyst
MR images showed a lobulated cystic lesion in the infra-patellar Hoffa’s fat pad.
Ganglion cysts of the knee joint usually originate from lateral meniscus or anterior cruciate ligament or posterior cruciate ligament, but they rarely arise from HFP and only a few cases have been reported in the literature.
1. Amin M, Torregiani W, Sparkes J. Infrapatellar ganglion that developed from infrapatellar fat pad and had minimal intraarticular extension. Knee Surg Sports Traumatol Arthrosc 2008;16:179-81.
2. Takatoma M, Kochioro I, Tanaka H, Taguchi T, Azuma E, Tanigawa Y, et al. A giant ganglion cyst that developed from infrapatellar fat pad and partly extended into the knee joint. Arthroscopy 2003;19:40.