They usually present as cosmetic concerns but may uncommonly have associated neurologic or vascular symptoms. If the cyst compresses an underlying nerve, the patient may report distal numbness or weakness. Vascular compression may cause coolness or cyanosis of areas distal to the cyst. The size of the cyst may vary over time and can increase after activity.
Although the exact etiology is unknown, it is likely that a small tear forms in a joint capsule or tendon sheath, allowing extravasation of synovial fluid into the adjacent tissue. When the fluid reacts with local tissue, it becomes more gelatinous and a cyst wall forms. While it has been postulated that ganglion cysts are caused by chronic joint inflammation, this theory is less likely because inflammatory changes are not seen in ganglion cysts.
Related topic: ganglion cyst of wrist
M67.4 – Ganglion
445008009 – Ganglion cyst
Differential Diagnosis & Pitfalls
- Lipoma – A freely movable, soft, fluctuant mass that does not transilluminate.
- Giant cell tumor of the tendon sheath – A firm, fixed swelling generally occurring on the flexor surfaces on the tendons in the region of the hand; does not transilluminate.
- Tenosynovitis – Diffuse swelling and bogginess of the tenosynovium overlying a tendon; usually tracks along the tendon in a longitudinal fashion.
- Neuroma – Less mobile and does not transilluminate.
- Soft tissue sarcoma (eg, fibrosarcoma) – Less mobile and typically not well circumscribed.
- Gouty tophus – A hard, nodular mass commonly found around the fingers, at the tips of the elbows, and around the big toe.
- Osteosarcoma – Immobile and not well circumscribed.
- Septic arthritis – Typically presents as an erythematous, warm, swollen joint; an effusion can often be detected.
- Artery aneurysm – Pulsatile, and a thrill may be palpated.