Diagnosis of biopsied tumor is an unpleasant surprise
I guess anyone can make an error in judgment and vets are no exception. About eight months ago, I had our vet look at our dog, who had developed a lump on the top of his head in the preceding few months. It was grape sized at the time and presented as firm and movable under the skin. Our dog is a 9-year-old Lab.
Our vet thought it likely to be benign and after a needle aspirate was inconclusive, told us to keep an eye on it. Fast forward to the
spring and since our dog needed a dental cleaning, we opted to remove the growth and have it biopsied at the same time.
We were surprised with the results coming back as a tumor called osteosarcoma, as was our doctor.
What can you tell me about this kind of tumor? I understand from reading online that osteosarcoma in dogs is a bad tumor and we are hoping for the best.
Veterinarians are no different than any others in making diagno- ses and judging what they find based on experience and available diagnostics. There is no fault in having done an aspirate and with inconclusive results, taking a wait- and-see approach. The only other alternatives would have been to do nothing and wait and see or to have removed the growth initially. Usually, well-encapsulated, nonattached masses are benign, as was suspected initially. Osteosarcomas in dogs are typically found on the bones of the legs and usually at either end of those bones. These more typical osteosarcomas don’t have a very good prognosis and I have seen many.
Finding osteosarcomas in other places, such as the top of the skull, is far less common and falls into another category known as multilobular bone tumors. These growths are not painful, and the good news is that with removal, prognosis is far better than in typical canine osteosarcoma, where leg amputation is often called for even though there are new alternatives available depending on case presentation.
Completely margin free surgical removal of these multilobular osteosarcomas can be a challenge. If the tumor was low grade, I expect your dog will do well. Other diagnostics include chest radiographs to rule out metastasis. If the tumor was higher grade, radiation may be considered. I would speak with your veterinarian about seeking a consult with an oncologist for next steps, but remember that these kinds of tumors have pretty good survival rates. Good luck.