We present a case of ganglion cyst of the knee treated arthroscopically. Ganglion cysts typically arise from the anterior or the posterior cruciate ligament. In this case of an anomalous location, a 3.5-cm mass arose directly from the anterolateral articular capsule, lying over the lateral meniscus, displacing Hoffa's fat pad and joining the pretibial bursa. We removed it arthroscopically using only medial portals to avoid cystic wall damage and fluid leakage from the lateral portal. Arthroscopic evaluation was performed starting from the inferomedial portal to assess the cyst location, and shifting to the mid patellar portal. From that portal, we were able resect the cyst, opening the wall and shaving and aspirating the myxoid fluid.