Large lateral meniscal ganglion cyst extending into the intercondylar fossa of the knee.

We report the case of a 31-year-old, otherwise healthy man with a large intra-articular meniscal ganglion cyst (27.7 x 13.5 mm) originating from the dorsal horn of the lateral meniscus. Clinically, the patient presented with knee pain in a squatting position. Magnetic resonance imaging revealed a large intra-articular cyst in the posterior compartment. At arthroscopic surgery, the ganglion cyst was found in the intercondylar space posteriorly to the posterior cruciate ligament. After removal of the ganglion cyst, a horizontal tear in the dorsal horn of the lateral meniscus was revealed and treated by partial meniscectomy. To our knowledge, a meniscal ganglion cyst originating from the lateral meniscus and extending into the joint is an extremely rare event, with only two previous reported cases. We review the current literature on the pathogenesis, distribution, and treatment of meniscal ganglion cysts.