It sounds like it was caught early enough that there is no further involvement.
You may be interested in the impact of diet on helping with the prognosis of this sort of cancer
http://www.marvistavet.com/html/body_nutritional_therapy.html
The epitheliotropic lymphoma is also known as mycosis fungoides (MF), so named because of the mushroom-like appearance of the tumors in humans. The most common sites for these tumors is in the mouth area.
As the vet found no lymph node involvement and no other tumors that is a positive thing. You may have gotten it early on presuming the path lab agrees with your vets analysis.
Your vet may suggest chemo (which is not as bad in dogs as it is in humans) or radiation treatment.
If the pathology comes back as cancer then you may want to work with a veterinary oncologist or have your vet consult with one while she works with your pet.
You can scroll down on this page to read about the problem in dogs and cats
http://www.vet.uga.edu/vpp/CLERK/Nesbit/
The above info on diet therapy in conjunction with chemo might be helpful to you if your vet's suggestion on diagnosis pans out.
Hope this helps you and I wish you luck with your dog!
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