HeatherCK11
I am sorry to hear about your mare.
When his biopsies were initially examined/tested I was only told that he had lymphoma, we did not yet know the specific form. From what I was told most forms of lymphoma in horses are fatal (with horses often only living weeks from the time of diagnosis).
So yes, you are right, there is world of difference in terms of prognosis between the forms of lymphoma and you won’t really know anything until you get the results of the biopsies.
However, if you get bad news, that is not necessarily a reason to give up hope as so little research has been done on treating lymphoma in horses.
Also, while I have been working with New Bolton they do not have an equine oncology department so we used vets in Australia for the oncology consult and treatment plan. They came to me highly recommended (by New Bolton) and obviously I have gotten positive results from their treatment plan.
http://www.vetoncologyconsults.com
Good luck!!!