“What do you think it is doc?”
That seems like a simple question. I’m asked it at least once everyday. Pet owners bring me a cat or a dog with a lump they just noticed. Or they want me to recheck a bump that has changed in some way–maybe it got bigger, or darker, or harder. They are worried. They would like an answer.
Truth is, I cannot easily tell what it is just by looking at a lump. Even with my trained hands, most bumps feel the same to me as they do to you. I need to get a sample of the cells from inside the lump to know what it is.
Sampling the lump is an easy, painless procedure I can do within the exam room. It hurts less than getting a vaccine. I take a fine needle aspirate of the lump by putting a sterile needle into the mass and withdrawing a small sample of cells. Next I spread the cells onto a glass microscope slide and stain them before I view them under the microscope. This is referred to as cytology (the study of cells.)
I am not a pathologist, but I am trained in basic pathology during veterinary school. Under the lense of the microscope I can quickly assess whether the lump appears to be a benign tumor or a more aggressive tumor. If it looks aggressive, I will recommend that we send the slide out for a board certified pathologist to review.
Once we have a potential diagnosis of what the lump is, then we can make a plan for how to treat it. Some lumps, such as benign fatty tumors (lipomas) we just monitor. If the lipoma becomes unsightly or interferes with the pet’s movement, then we can do a sort of “liposuction” to reduce the size of the mass. Other lumps require different therapies.
For example, a lump that appear to be a cancerous tumor called a sarcoma, needs prompt surgery. These types of lumps must be cut away with wide margins to prevent the aggressive cancers from spreading. For a sarcoma, the chance to do surgery is the chance to cure. Watching and waiting would be a bad choice for this type of tumor.
Other lumps might be a mast cell tumor. Mast cells are normally part of the skin. Their job is to release chemicals called histamines to rid the body of foreign proteins that challenge the immune system. Mast Cell Tumors can cause serious allergic reactions if you squeeze them, or “anger” them while trying to remove them. For these types of tumors, we must pretreat the pet with antiinflammatories such as prednisone and antihistamines to prevent complications. This type of tumor also tends to quickly spread (metastasize) to internal organs. Sometimes it has already spread by the time we diagnose it on the skin. So we “stage” this tumor prior to attempting surgery. Staging includes full bloodwork, X-rays, and ultrasound imaging to try and find any swollen lymph nodes or other evidence of metastasis prior to surgery.
One type of lump, a histiocytoma, can resolve on its own within a month or two if we can be patient. These lumps commonly appear on the legs, trunk, and face of younger dogs. We can treat these with topical ointments until they resolve. If the histiocytoma doesn’t resolve, or if it starts to bleed and ulcerate, then we schedule surgery.
The oddest lump I ever found on a dog in Florida was one with a coiled up, two-foot long worm inside it. The veterinary pathologist identified the worm as Dracunculis. This worm is known as “Guinea Worm” in Africa and it is a massive public health problem there. The worm is transmitted by drinking contaminated water. The parasite migrates through the body and finally matures on the lower legs as a painful lump on the infected person or animal. When the person wades into water, the worm extends its reproductive parts out of the lump and spreads more Dracunculis eggs into the water, continuing its life cycle. The treatment for removing the parasite from a person’s foot or leg is to slowly coil up the worm around a small stick over several weeks. In fact, the medical logo (caduceus) is a symbol of a Dracunculis worm being coiled around a stick. The Jimmy Carter Center has been working to eradicate this parasite from Africa. Fortunately, the species of Dracunculis I found in the Florida dog was not the same as the one from Africa. Instead, this form is transmitted by raccoons and usually only affects wildlife.
[See: http://cartercenter.org/health/guinea_worm/mini_site/facts.html%5D
So, when you ask your veterinarian to check a lump or a bump, expect them to ask for permission to do a few more tests. You might end up with good news. But if you don’t, your veterinarian will guide you as to the best plan of action.
Have you ever noticed a lump or a bump on your pet and wondered what it was? Did your veterinarian help you get a diagnosis? I’d be interested in hearing your experiences.
Kibble 