Intratendinous Ganglionic Cyst of Semimembranosus: A Rare Cause of Thigh Swelling

Ganglionic cysts are common swellings of the hands. Various mechanisms are thought to generate these lesions, such as cystic mucoid degeneration and inflammation. Typically, ganglionic cysts are asymptomatic but can cause pain. They usually originate from soft tissues like ligaments, joint capsules, and sheaths of tendons. We present the case of a 37-year-old man with mid-thigh swelling with intermittent mild pain. However, no systemic symptoms like fever or weight loss were present. Workup unmasked the presence of a rare intratendinous ganglionic cyst. Ultrasonography (USG) and magnetic resonance imaging (MRI) can confirm the presence of ganglionic cysts and estimate their sizes and relationships with the surrounding structures. Treatment options range from observation and conservative management to interventions like aspiration and surgical excision.