hygromas

A hygroma is a benign, fluid-filled cyst that forms near joints or tendons. They are most often described as ganglion-type cysts, such as wrist ganglions or digital mucous cysts on the fingers. A related term, cystic hygroma, denotes a congenital lymphatic malformation (lymphangioma) usually occurring in the neck or armpit; this is a different entity from ordinary hygromas.

Common sites include the dorsal wrist, the fingers near the distal interphalangeal joint, and less commonly the knee or foot. Digital mucous cysts are often associated with osteoarthritis of the distal interphalangeal joint.

The exact origin of hygromas is not fully understood. Most arise from mucin production by synovial cells or from herniation of the joint lining into soft tissue. Repetitive minor trauma and degenerative joint disease are considered risk factors, and a direct joint connection can be present in some cases but is not universal.

Diagnosis is usually clinical, with a firm, rounded, mobile lump that may be tender if irritated. Imaging with ultrasound confirms a fluid-filled structure and can assess for connection to a joint; MRI may be used in complex cases. Aspiration can aid diagnosis and may provide temporary relief, but recurrence is common.

Treatment ranges from observation for asymptomatic lesions to aspiration with or without corticosteroid injection. Surgical excision is considered for persistent or bothersome cysts, or when a stalk is implicated. Recurrence after treatment is possible, but the prognosis for hygromas is generally excellent, given their benign nature.