A cystic hygroma is a sac-like structure with a thin wall that most commonly occurs in the head and neck area.

A cystic hygroma is a birth defect. It occurs as the baby grows in the womb from pieces of material that carries fluid and white blood cells. Such material is called embryonic lymphatic tissue. After birth, a cystic hygroma usually looks like a soft bulge under the skin. The cyst can't be seen until after birth, and sometimes is not noticed until the person is older.

A common symptom is a neck mass found at birth, or discovered later in an infant after an upper respiratory tract infection.

• Chest x-ray
• Ultrasound
• CT scan

Treatment involves complete removal of the abnormal tissue whenever possible. However, cystic hygromas can often invade other neck structures, making this impossible.

Other treatments have been attempted with only limited success. These include:

• Chemotherapy medications
• Injection of sclerosing medications
• Radiation therapy
• Steroids

The outlook is good if surgery can totally remove the abnormal tissue. In cases where complete removal is not possible, the cystic hygroma commonly returns.

Complications may include:

• Bleeding
• Damage to structures in the neck caused by surgery
• Infection
• Return of the cystic hygroma

If you notice a lump in your neck or your child's neck, call your doctor.