MRI Misinterpretation of a Large Infrapatellar Fat Pad Ganglion of the knee: A Case Report and Literature Review

Ganglion cysts of the infrapatellar fat pad (IPFP) in the knee are extremely uncommon and are not associated with meniscal tears. We report the case of an extensive large multiloculated IPFP ganglion cyst invading the meniscus that was associated with a meniscal tear, which to our knowledge is the first of its kind reported. In the case of a 52-year-old gentleman, clinical and radiological evidence led to the impression of a meniscal tear and a parameniscal cyst. Histopathological examination after open surgical excision refuted the suspected diagnosis and confirmed presence of an IPFP cyst. Although magnetic resonance (MR) imaging is the modality of choice, caution is advised to radiologists in differentiating these cystic lesions. We recommend consideration for the use of fat suppressed contrast-enhanced MR imaging for a more accurate diagnosis of cystic lesions of the knee.