A case of intra-articular ganglion cysts of the knee joint: correlation between arthroscopic and magnetic resonance imaging

BACKGROUND Intra-articular ganglion cysts of the knee are rare. Here we report a case of an arthroscopically confirmed ganglion cyst arising from the posterior cruciate ligament (PCL) along with preoperative magnetic resonance imaging (MRI) findings. CASE PRESENTATION A 39-year-old female admitted a hospital with left knee pain with flexion and extension. MRI revealed a cystic lesion along the PCL. The lesion exhibited slight but homogeneous hyperintensity on T1 weighted images. Thin septals were visible within the lesion. Arthroscopic examination revealed a mass lesion with a white fibrous capsule, located near the PCL. A gel-like liquid spurted from the mass upon puncture. The lesion was completely resected. Histological examination revealed loose connective tissue and fibroblasts with collagen, thus confirming the diagnosis of a ganglion cyst. CONCLUSION Many reports have suggested intra-articular ganglion cysts of the knee are rare. In our study, a cystic lesion may have been impinged between the PCL and intercondylar notch, resulting in flexion and extension difficulty in the left knee. Arthroscopic resection is the major treatment of intra-articular ganglion cyst, and preoperative MRI findings can predict the correct arthroscopic approach. We have reported a case in which an intra-articular ganglion attached to the PCL.