I think you would be correct that this is lymph fluid. I would mention this to your team. The lymphoedema can be pretty extreme in terms of how swollen the face/neck gets. It has taken a good 12 months for Kris's lymphoedema to subside so that we both hardly notice it. But then he did have bilateral RND.
Talk to your team about the leak. They may have to treat this to halt the leak.
Best wishes,
Tammy

Caregiver/advocate to Husband Kris age 59@ diagnosis
DX Dec '10 SCC BOT T4aN2bM0 HPV+ve.Cisplatin x3 35 IMRT.
PET 6/11 clear.
R) level 2-4 neck dissection 8/1/11 to remove residual node - necrotic with NED
Feb '12 Ca back.. 3/8/12 total glossectomy/laryngectomy/bilat neck dissection/partial pharyngectomy etc. clear margins. All nodes negative for disease. PEG in.
March 2017 - 5 years disease free. Woohoo!