Rare cases of intramuscular ganglion cysts in the gastrocnemius muscle of the calf have been reported. It is possible for a cyst to be considerably displaced from the joint. In one extreme case, a ganglion cyst was observed to propagate extensively via the conduit of the common peroneal nerve sheath to a location in the thigh; in such cases surgery to the proximal joint to remove the articular connection may remove the need for a riskier, more extensive surgery in the neural tissue of the thigh. The cysts may intrude into the spine, which may cause pain and dysesthesia in distant extremities.Cystic adventitial disease, in which a cyst occurs within the popliteal artery near the knee, has been proposed recently to occur by an articular mechanism, with a conduit leading from the joint, similar to the development of ganglion cysts, that spreads within the peroneal nerve.Cysts that were compressing one or more nerves and causing bone erosions have been reported to occur near the shoulder joint. Causes
The most commonly accepted probable cause of ganglion cysts is the "herniation hypothesis", by which they are thought to occur as "an out-pouching or distention of a weakened portion of a joint capsule or tendon sheath." This description is based on the observations that the cysts occur close to tendons and joints. The microscopic anatomy of the cyst resembles that of tenosynovial tissue. The fluid is similar in composition to synovial fluid. Dye injected into the joint capsule frequently ends up in the cyst, which may become enlarged after activity.
Although most commonly found in the wrist, ganglion cysts also may occur in the foot.Ganglion cysts are "commonly observed in association with the joints and tendons of the appendicular skeleton, with 88% in communication with the multiple small joints of the hand and wrist and 11% with those of the foot and ankle". Wrist
They commonly are found near the wrist joint, especially at the scapholunate area.Common wrist ganglions include:

dorsal wrist ganglion
volar wrist ganglion
volar retinaculum ganglion
extensor retinaculum ganglion
occult ganglion
intraosseous ganglion
mucous cyst

Foot
In a 2007 study of patients in Glasgow whose foot lumps were removed surgically, 39 of 101 cases were ganglion cysts. The study replicated earlier findings that no ganglion cysts were found on the sole or heel. The authors wrote, "Although lumps in these areas may be ganglia, the surgeon should probably consider other diagnoses in the first instance." The researchers noted a preponderance of occurrence among females (85%) and that 11 of the other cases had been misdiagnosed as ganglion cysts before surgery.Ganglion cysts are not limited to the hands and feet. They may occur near the knee, commonly near the cruciate ligaments, but they may occur at the origins of the gastrocnemius tendon, and anteriorly on Hoffas infrapatellar fat pad. At the shoulder, they typically occur at the acromioclavicular joint or along the biceps tendon. Other
From their common origin at a joint or tendon, ganglion cysts may form in a wide range of locations. Rarely, intraosseous ganglion cysts occur, sometimes in combination with a cyst in the overlying soft tissue.