Ami, I am sorry to have not seen this post earlier, travelled for work last Thursday and caught the flu while on the plane.
I will pray for positive outcome of the biopsy(ies) and a quick and total recovery. Understand that sometimes they (biopsies) will still be inconclusive (our oldest, Justin, has been fighting off papillary thyroid carcinoma for a few years). In your sister's case, I hope that if it is thyroid cancer, that it is the easier of the four to treat.
Papillary thyroid cancer can be treated post-surgery to address impacted lymph nodes anywhere in the body via either minor surgery or radioactive iodine therapy (the "smart bomb" approach). It is also 95% "curable", not just "treatable" in cases when caught early. In Justin's case, he went back for surgery to remove two series of lymph nodes that were not discovered in the first surgery, along with more than 50 additional nodes that ultrasound showed to be "reactive". Only the two that were known (via FNA) to be cancerous ended up being positive on post surgical biopsies. The other nodes were tested for everything under the sun and they suspect that he had been subjected to an exotic virus - never found out. He is scheduled to be back this Friday for third round of ultrasound and biopsies, but we can see the light at the end of the tunnel (not that one!).
In any case, PM me if you have any questions, our caregivers in Children's Hospital have been fantastic advocates on his behalf and we have a wealth of information. Glad to see that she has a supportive family, and I hope you explore other hospital options.