Causes of cystic hygroma
The exact cause of a cystic hygroma is unknown. The cyst forms as a result of damage to the lymphatic system during fetal development, or as a result of physical trauma or respiratory infection in cases that affect adults. Damage to the lymphatic system causes lymph fluid to collect under the skin instead of flowing through your bloodstream, causing a bulge or sac-like growth of fluid. Studies suggest that cystic hygromas could be the result of environmental factors like smoking or drinking alcohol during pregnancy. Other studies suggest that genetic changes or mutations that affect the development of the lymphatic system cause cystic hygromas. Often, cystic hygromas form on their own, but some form in combination with genetic conditions like Down syndrome, Turner syndrome or Noonan syndrome.