Can fetus die from cystic hygroma?

No, but: The underlying chromosomal problem may be fatal.

Not always.: This is a condition that is a congenital multiloculated lymphatic lesion that can arise anywhere. It is classically found in the left posterior triangle of the neck, and contains large cyst like cavities containing watery fluid. This is benign, but a lethal version, cowchock wapner kurtz syndrome, causes cystic hygroma, lymphedema and cleft palate.

Rarely: In some cases of 45X (Turner syndrome), the hygroma has become so massive--perhaps larger than the fetus, that the demise may have been related to the massive extracellular volume overload. The mere presence of a cystic hygroma increases the risk of congenital heart defects, or a chromosomal disorder, which in themselves may pose a threat to fetal survival greater than the hygroma itself.