Is the lump hard or soft?
Does it seem to be attached or just under the skin?
Dogs are prone to all types of lumps and bumps. I understand your fear and will try to tell you what may be happening. Dogs can get Lipomas which are benign fatty type tumors very common and can very well be what you are seeing. They are usually right under the skin and not attached. The lymph nodes are also in that area which can indicate an infection somewhere in the body, it may be a sebaceous cyst, which is a cyst that lies below the skin. Sebaceous cysts, are also called epidermal inclusion cysts and infundibular cysts, are pretty common in dogs. There are other cysts that are very common in dogs like a sweat gland cyst. There are many other types of problems that can cause the type of lump you have described. The Vet will do a needle biopsy and be able to tell you exactly what is going on. Joan