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Synonyms: Lymphangioma.

Definition: Congenital cystic mass of the neck. The most common form of lymphangioma¹¹.

Case report: A male infant was diagnosed prenatally at 20 weeks of gestation with anterior cervical cystic hygroma. The mother was a 31-year-old gravida 3, who had an otherwise uncomplicated pregnancy. She underwent a c-section (because of the baby’s huge neck mass). Postnatally, the diagnosis of cystic hygroma was confirmed. The tumor was a very large lymphangioma with hemangiomatous component and was located in the midline of the anterior neck, extending to the chin and lower lip. The baby’s karyotype was normal. No additional anomalies were identified. Immediately after birth he was admitted to the NICU for respiratory distress and surgical intervention. He underwent surgical resection of 2/3 of his cystic hygroma and placement of a temporary drain. Upon removal of the drain, fluid rapidly re-accumulated, and he underwent tracheostomy to combat airway obstruction. He experienced several episodes of internal bleeding into the cervicofacial cysts requiring transfusions for anemia. MRI revealed mixed but primarily multicystic hygroma expanding to the lower eyelids, retropharynx, and into mediastinum behind the aortic arch. These were deemed inoperable at this point. The baby also developed an airway infection with staphylococcus aureus in his tracheostomy tube. Two months after his birth, the lymphangioma apparently hemorrhaged into his airway causing airway obstruction and resulted in his death.

Etymology: Gr. kustiV  bladder, sack and . Ugroma = a formation made of fluid.

Prevalence: Unknown, but very rare for isolated cystic hygromas of the anterior part of the neck. To the author’s knowledge, only 2 additional cases of anterior nuchal cystic hygroma have been published30, .

Etiology: There is a recognized association between fetal cystic hygroma and chromosomal abnormalities18,19,20.  Alcohol has also been incriminated as a teratogen . Otherwise, the etiology is unknown.

Pathogenesis: Cystic hygroma is thought to arise from an early sequestration of embryonic lymphatic channels, as suggested by Dowd  in 1913 and expanded on by Goetch in 1938 . This sequestration apparently occurs more commonly in the developing jugular lymph sack pair than in the other four embryonic sites of the lymphatic system. From this location, the sequestered site follows the path of the surrounding mesenchyme destined for either the neck or the developing mediastinum. This accounts for the propensity of these lesions to occur in the lower neck, axilla, and upper mediastinum . Alternatively, a cystic hygroma may arise from a failure of the juguloaxillary lymphatic sac to drain into the internal jugular vein, producing a congenital obstruction of lymphatic drainage , , . Some authors have proposed that involution of a cystic hygroma in utero produces the “web neck” of Turner syndrome , .

Location: Approximately 75%-80% of all cystic hygromas involve the neck and the lower portion of the face . In children, the most common location is the posterior cervical space, followed by the oral cavity11. These lesions are characteristically infiltrative in nature and do not respect fascial planes. Consequently, they may extend inferiorly from the posterior cervical triangle into the axilla and mediastinum or anteriorly into the floor of the mouth and the tongue . If the mass is very large, it may extend across the midline , . Only 3%-10% of cervical cystic hygromas are associated with extension into the mediastinum ,14.

Sonographic findings: On ultrasound scans, most isolated cystic hygromas of the neck manifest as a multilocular predominantly cystic mass with septa of variable thickness . The echogenic portions of the lesion correlate with clusters of small, abnormal lymphatic channels16. Fluid-fluid levels can be observed with a characteristic echogenic, hemorrhagic component layering in the dependent portion of the lesion . Prenatal ultrasound may demonstrate a cystic hygroma in the posterior neck soft tissues10.

Implications for targeted examinations: There is a recognized association between fetal cystic hygroma and chromosomal abnormalities , , . Turner’s syndrome is the most common , although trisomy 1310, , trisomy 18 , trisomy 21 , and Klinefelter’s syndrome  have been reported. Thus, fetal karyotyping should be offered. In addition, careful fetal echocardiography is recommended.

Differential diagnosis:  Thyroglossal duct cyst, branchial cleft cyst, (dermoid and epidermoid cyst), bronchogenic (visceral) cyst11, hamartoma of the mandible and cervical thymic cyst11 are all differential diagnoses for cystic hygroma of the anterior neck. Encephalocele and meningocele should be added for lesions of the posterior neck.

Associated anomalies: Noonan’s syndrome , multiple pterygium syndrome , polysplenia syndrome, Pena-Shokeir, or Robert’s syndrome  are more common in fetuses with normal karyotypes21.  Hydrops fetalis is the extreme condition where generalized edema, ascites, and pleural effusion occur. Ideally, the term “cystic hygroma” should be used only to describe large, localized accumulations of lymphatic fluid .

Prognosis: Widely disparate prognoses accompany cystic hygromas. These are dependent on genetic associations and the timing of discovery . According to Thomas30, the prognosis should be divided into four categories:
1) first trimester, normal karyotype: good;
2) first trimester, abnormal karyotype: poor;
3) second trimester and early third: poor to guarded; and
4) mid to late trimester: good.
Very large masses may compromise the airway by extrinsic pressure resulting in death. To avoid this outcome, early tracheostomy is required . Although these masses usually grow slowly, they may suddenly increase in size secondary to hemorrhage or trauma or because of a viral infection when large amounts of lymphatic fluid are produced from the lymphoid follicles in the cyst wall . Other reported clinical manifestations include fascial nerve paralysis, dysphagia, or other feeding problems . Chylothorax and chylopericardium may occur as complications of mediastinal involvement11.  Spontaneous regression during uterine life is also possible, especially in fetuses with Turner or Noonan’s syndrome and this has been used as explanation for the webbed neck seen in children with these conditions10, . The prognosis for hydrops fetalis is dismal .     

Recurrence risk: It depends on whether the fetus has abnormal karyotype or not. In the first case, the families can be assured that these chromosomal defects are usually sporadic and that there is only a small increased risk with subsequent pregnancies21. Fetuses with normal chromosomes appear to have a much higher incidence of consanguinity or a previous history of abnormal fetuses21.  

Management: Prenatal drainage is unhelpful. In severe cases, termination of pregnancy should be considered. In milder cases, surgical removal may be considered after birth. Thus, maternal transfer to a perinatal center, where expert neonatal, respiratory, and pediatric surgical care is immediately available is advisable21.