My aunt has cystic hygroma but doctors wont operate on her because she has a rare case of it. What can we do?

Rare meaning what ? Cystic hygroma is a well known benign entity that is commonly found in the neck as a single mass but may occur as several smaller sites in different locations. In trained hands many can be partly or completely removed but the location & nearby structures may make surgery risky. Try to find out if this is the case & pursue a second opinion if you desire.