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At a glance

Cystic hygroma (CH) is a benign, multiloculated cystic structure. They may occur anywhere in the body, although they are most frequently encountered in the neck and axilla. CHs frequently abut and/or encompass neurovascular structures.

Synonyms

Cystic Lymphangioma; Familial Nuchal Bleb; Fetal Cystic Hygroma; Hygroma Colli; Cavernous Lymphangioma.

Incidence

Approximately 1-2:6,000 live births are affected by a CH.

Genetic inheritance

CH with a normal karyotype may rarely be inherited as an autosomal recessive trait.

Pathophysiology

CHs are benign masses of multilocular cysts of different sizes (microcysts with a diameter of <1 cm, macrocysts with a diameter ≥1 cm). In general, macrocystic hygromas are less invasive, surgically easier to remove and respond better to sclerotherapy than microcystic lesions. The size of CHs can range from small lesions to giant, thin-walled cystic masses that can grow larger than the fetal head. The cysts may result from a lymphatic abnormality, possibly secondary to absent or nonfunctional connections between the lymphatic and venous systems. The concept that in some fetuses the correct communications between these two systems will develop later during gestation may account for cystic areas that resolve with merely a residue of redundant skin (pterygium colli) remaining (eg, as in ☞Ullrich-Turner Syndrome). Other theories addressing the development of CHs include possible abnormal sequestration of embryonic lymphatic tissue that does not communicate with the normal lymphatic flow channels.

Diagnosis

Prenatal diagnosis is often possible (ultrasound). In approximately two-thirds of children the CH is already identifiable at birth, and in 90% it will present within the first 2 years of life as it increases in size. Most often, the lesion is a cosmetic problem; however, compression of airway, esophagus, and/or great vessels may occur as the hygroma grows and invades the deeper structures of the neck or the mediastinum. The clinical course is variable and can be characterized by steady state, intermittent and/or progressive growth, or spontaneous regression, and can be modified by hemorrhage and/or infection.

Clinical aspects

CHs, most often occurring in the neck (75%) and axilla (20%), belong to the group of lymphatic malformations. Occasionally, cystic neck hygromas become very large and extend into the mouth (tongue, hypopharynx, supraglottic region), mediastinum, axilla, and/or chest, or they occur exclusively in those areas. Depending on their location, hygromas can cause mild-to-profound respiratory distress and swallowing problems with dehydration and failure to thrive. CHs are often associated with localized lymphedema and congenital cardiac defects. In approximately half of the patients, fetal CHs are associated with chromosomal anomalies, most frequently ☞Ullrich-Turner Syndrome and ☞Trisomy 21, but also ☞Trisomy 18, and ☞Noonan Syndrome. Other associated anomalies may include cleft lip/palate, single umbilical artery, and horseshoe, fused, or ectopic kidneys, umbilical hernia, thymic aplasia, or arrhinencephaly/holoprosencephaly. The risk of infection of a CH is approximately 15-20% and may initially result in additional swelling, pain, fever, and localized erythema. Long-term though, infection and inflammation occasionally lead to shrinkage of the hygroma secondary to fibrosis. The risk of hemorrhage is approximately 10 to 15%. This complication should be considered in any patient with an enlarging and painful CH and evidence of acute blood loss. Surgical therapy remains the treatment of choice for large CHs, but complete resection without causing damage to vital structures is often not possible and is therefore associated with a high-recurrence rate (particularly for CHs with suprahyoidal extension). Smaller or residual lesions after surgery may be treated with laser therapy or repeated sessions of sclerotherapy injections (eg, bleomycin, OK-432 [Picibanil], doxycycline, sodium tetradecyl sulfate, alcohol, or Ethibloc) (a corn-protein derived alcohol ...

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