From the Guidelines
Cystic hygroma is primarily caused by lymphatic dysplasia, which is often associated with chromosomal abnormalities such as Turner syndrome (45,X) and Down syndrome (trisomy 21), leading to impaired communication between the lymphatic system and venous drainage. This condition is a type of nonimmune hydrops fetalis (NIHF), which can result from various etiologies, including cardiovascular, chromosomal, hematologic, infectious, and lymphatic abnormalities 1. The development of cystic hygroma is closely linked to the formation of the lymphatic system during fetal development, and genetic factors play a significant role in its pathogenesis.
Key factors that contribute to the development of cystic hygroma include:
- Chromosomal abnormalities, such as Turner syndrome and Down syndrome, which account for a significant proportion of cases 1
- Lymphatic dysplasia, which impairs the communication between the lymphatic system and venous drainage 1
- Impaired venous return, which can result from various mechanisms, including cardiovascular malformations and thoracic abnormalities 1
- Genetic disorders, such as alpha thalassemia, which can increase the risk of developing NIHF 1
The exact role of environmental factors during pregnancy in the development of cystic hygroma is less understood, but it is believed that they may contribute to the condition in some cases. The blocked lymphatic vessels cause lymph fluid to accumulate in sacs or cysts, which can vary in size and may grow over time. While some cases resolve spontaneously before birth, others require treatment after delivery, which may include surgical removal, sclerotherapy, or drainage procedures depending on the size and location of the cystic hygroma. Diagnostic testing is recommended to identify the underlying cause of NIHF, including chromosomal abnormalities and genetic disorders 1.
From the Research
Causes of Cystic Hygroma
- Cystic hygroma is a developmental abnormality of the lymphoid system that occurs at sites of lymphatic-venous connection, most commonly in the posterior neck 2.
- It is frequently associated with karyotypic abnormalities, various malformation syndromes, and several teratogenic agents 2.
- The disease is the result of a defect in the embryonary development of the lymphatic system 3.
- Cystic hygroma can occur either as an isolated finding or as a part of a syndrome, with associations to chromosomal abnormalities such as Trisomy 21,13,18, and Turner syndrome, as well as non-chromosomal syndromes like Noonan Syndrome 4.
Associated Factors
- Increased nuchal translucency and cystic hygroma have been associated with a wide range of structural and genetic abnormalities 4.
- Approximately 50% of Noonan Syndrome cases are caused by mutations in the PTPN11 gene, which can be associated with cystic hygroma 4.
- Chromosomal abnormalities were found in five cases of fetuses with cystic hygroma, including Turner's syndrome and Downs' syndrome 5.
- The presence of septae in cystic hygroma and amniotic fluid alpha-fetoprotein (AFP) levels are prognostic indicators 5.