What does it mean to have a cyst on the arm?

Hello, Based on the symptoms and location described in your query, if a cystic mass is detected on the arm, it is commonly attributable to a ganglion cyst. Ganglion cysts are secondary manifestations of chronic tenosynovitis and frequently occur around the wrist and elbow joints. With prolonged tenosynovitis, localized accumulation and encapsulation of fluid may form a cyst wall, resulting in a dome-shaped or round, raised mass protruding beneath the skin. We recommend consulting a qualified orthopedic specialist at a reputable hospital. I hope this information is helpful. Wishing you good health!