CYSTIC HYGROMA WITH NON IMMUNE FETAL HYDROPS

14 WEEKS GESTATION FOR NT SCAN

Diffuse subcutaneous edema of fetal thorax and abdomen with mild bilateral pleural effusion

Large cystic fluid collection in the nape of neck extending to both sides with few internal septations and diffuse subcutaneous edema of fetal cranium

·        Nuchal cystic hygromas are characterized by single or multiple congenital cysts of the lymphatic system most commonly found within the soft tissues of the neck.

·        The frequency is one in 875 spontaneous abortions.

·        Nuchal cystic hygromas are the clinical consequence of a delay in  development or absence of the communications that normally develop between the jugular lymph sacs and the internal jugular veins at approximately 40 days gestation.

·        The obstructed jugular lymph sacs dilate along the paths of least resistance into the posterior and lateral cervical areas.

·        Late communication of the sacs with the internal jugular vein may be manifest by redundancy of the posterior nuchal skin, neck webbing, and elevation and anterior rotation of the ears.

·        Complete lymphatic obstruction may be associated with nonimmune fetal hydrops, which is frequently fatal.

·        About 78% of patients with cystic hygroma are chromosomally abnormal; 58% have a karyotype associated with Turner syndrome phenotype; while autosomal trisomies and various structural abnormalities made up the remaining 20%.

·        The most common associated structural malformations are cardiac abnormalities.

·        Even among the 22% of fetuses with normal chromosomes, various physical anomalies are present.

·        Other syndromes associated with cystic hygromas are Noonan syndrome (autosomal dominant), Pena-Shokeir syndrome, Down syndrome, Robert’s syndrome (autosomal recessive) and multiple pterigium syndrome (autosomalrecessive, X-linked).

Ultrasonographic findings

·        The fetus presents with large bilateral cystic areas, termed cystic hygromas develop within the skin in the posterolateral aspect of the neck.

·        They may grow so large that they lie adjacent to each other.

·        It then appears that there is a cystic mass arising from the back of the neck with one to three septa in the center.

·        The skin thickening is most pronounced in the upper torso and cranium.

·        Hydrops occurs in more severe cases with large pleural effusions, pericardial effusions and ascites.

·        Amniotic fluid is often reduced.

·        Placenta is normal or thickened with hydrops.

·        Differential diagnosis is encephalocele or meningocele (the mass is posterior and is a single mass. It is associated with a cranial defect) and unfused amniotic membrane.

Reference : Antenatal Diagnosis and Management of Nuchal Cystic Hygroma: A Case Report in the Yaounde Central Maternity, Cameroon; Clinics in Mother and Child Health; Vol. 8 (2011).