A cystic hygroma is a congenital lymphatic malformation, usually a macrocystic lymphatic malformation, containing lymphatic fluid. It most commonly occurs in the posterior triangle of the neck, but can occur in the axilla and other sites.
Cystic hygromas may be associated with chromosomal abnormalities, such as Turner syndrome, trisomy 21, 18 or 13, and congenital cardiac abnormalities.
It may be seen on antenatal scans, picked up during routine baby checks, or discovered incidentally later.
Key Features
Cystic hygromas most commonly present in the neck or axilla. The key features include:
- Very large
- Soft
- Non-tender
- Transilluminate (the whole structure lights up when a pen torch is held flat against the skin)
Complications
Depending on the location and size, cystic hygromas can interfere with feeding, swallowing or breathing. It can become infected, in which case it will turn red, hot and tender. There can be haemorrhage into the cyst.
Management
Treatment varies based on the size, location and complications. Watching and waiting can be appropriate as it is a benign condition. Spontaneous regression can occur, but complete resolution is uncommon.
Treatment options include:
- Aspiration (giving temporary improvement)
- Sclerotherapy
- Surgical removal
Rarely, large neck lesions may cause airway compromise and require urgent specialist management.
Last updated June 2026
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