Atypical Presentation of Gouty Tophus as Posterior Cruciate Ligament Cyst: A Case Report

Gouty tophi generally develop around 10 years after the first attack of gout in untreated patients and are commonly found around feet, hands, and elbows. However, tophi can also occur as first sign of disorder. Tophaceous gout presenting in young at the posterior cruciate ligament (PCL) is extremely rare and difficult to diagnose because of its atypical presentation and no hallmark features in magnetic resonance imaging (MRI).

Here, we report a 25-year-old man manual worker with no prior history of gout has presented with left knee pain and locking episodes for 3 weeks, X-ray shows no abnormality, on advanced imaging with MRI, a well-defined cyst noted adjacent to PCL toward lateral aspect. During arthroscopy, a cyst was seen between anterior cruciate ligament and PCL with the extrusion of chalky paste-like material on puncturing the cyst. The tophus was biopsied and excised arthroscopically with excellent outcome.

This case report demonstrates that gout does not only always cause severe joint pain from inflammatory arthritis, but can also cause mechanical pain and locking of joint atypically presenting as intra-articular tophi. Hence, gout should also be considered in differential diagnosis of intra-articular cyst. Arthroscopic removal and continuous urate-lowering therapy provide excellent outcomes for such atypical presentations.