Ganglion cysts are benign soft tissue lesions that are most commonly found on the hand and wrist (also can be on feet).  They are often formed after repetitive trauma but many times the cause is unknown.  These lesions are found adjacent to the small joints in the hand/wrist or along tendons.

Remember to keep other lesions on your differential, such as epidermal inclusion cysts, giant cell tumors of tendon sheath, lipomas, pyogenic granulomas, abscess, and sarcomas. 

Management

• Most lesions resolve in a few weeks without intervention; therefore, observation of the lesion is usually advised as a first approach
• Hand surgeon referral: Cysts frequently reoccur after aspiration and sometimes require surgical excision

Sources

• Peter M. Murray. Chapter 27. Soft Tissue Neoplasms: Benign and Malignant. Hand, Elbow & Shoulder: Core Knowledge in Orthopedics.