My dog's facial tumor: Was melanoma diagnosis a misdiagnosis?

Thank you for submitting your question regarding Dylan. A procedure known as a fine needle aspirate is used to diagnose tumors just below the skin. A small sample of cells are collected from the mass and evaluated under the microscope. If this was not done when the mass was originally called a lipoma then then diagnosis could have been incorrect. If this procedure was performed then there are two things that could have happened. First, I have seen cancerous masses that have fat cells interspersed throughout them. So the sample collected could have only revealed fat cells, while there were mast cells present that did not show up on the slide. The other scenario is that the original mass was a lipoma and a mast cell tumor has grown over it in the past several years. I have seen this happen as well. I hope this information helps!

This is a mass (tumor), however, a wart is also a tumor. So the fact that something is a tumor does not necessarily mean that it is malignant. It could also be a benign mass. I would actually consult with her oncologist, as he will have seen many different tumors and will likely have an idea what it could be before doing a fine needle aspirate to determine the type, It will also be important to see this in connection with her melanoma and its prognosis, to determine whether this mass can be left alone due to the life expectancy of your dog, or to see whether this may be a metastasis or unrelated. Unfortunately this mass is in a tricky spot, so removal will be easy, but closing the skin defect will be hard as there is not so much skin available. This is why it is important to have it examined before it gets too big and the skin cannot be closed anymore due to having to remove too much skin with the mass. Please let me know if you have any other questions or concerns and I would be more than happy to help you further. Please take the time to mark this question as helpful or not as it helps us to improve on the quality of our answers to other pet owners. Thank you kindly!

Hello, and thanks for using Petco Pet Education Center, formerly Petcoach. A needle aspirate is the standard way to get an initial "suspected" diagnosis on a lump, but there are limitations to what a needle sample can tell us. If the cells in the needle sample appear worrisome, then the next diagnostic step is to send in a biopsy (surgical "chunk") of the tumor, or to remove the tumor itself and send the whole thing in to the lab for analysis. So, was removal of the ear necessary? I can't say, I don't know enough about the location or size of the mass. I didn't see the slide from the initial needle aspirate. But if the needle aspirate looked worrisome, and the next step is to remove the tumor or cut a piece of the tumor off, then removing that piece of the ear may have been the only way to find out for sure what the tumor was, and whether surgical removal was curative. Rather than regretting in hindsight that the surgery was done because the histopathology report came back as a histiocytoma, I would be focusing on the good news that Tate doesn't have a malignant mast cell tumor. And removal and lab analysis of the tumor was the only way you could have gotten that news. Hope this helps!

Thanks for using Petco Pet Education Center, formerly Petcoach! This does not mean that he is getting cancer necessarily. It could be a change in pigmentation. The lump may be a benign or malignant growth. This could even be an infection. This cannot be completely assessed just by looking at pictures or a description and usually requires sampling such as fine needle aspiration to determine its origin. Sometimes a biopsy is needed for a definitive diagnosis. I recommend that you have him evaluated by your veterinarian for further assessment and treatment. I am really hoping for something benign. Good luck and have a good day!

Hi, thanks for using Petco Pet Education Center, formerly Petcoach! It depends on the Vet's experience with reading cytology. Most Vets send out their cytology samples to a specialist who is trained to read them. Mast cell tumors have a classic look and tend to be one of the easier tumors to diagnose. You could ask your Vet to send the slides out since that only takes 1-2 days to get them back but sometimes aspirates do not get you an answer. I know you have surgery set up and a biopsy planned. That is the best thing for Precious, to get the mass off and know what it is. It has a high chance of being benign. It is a good thing it hasn't grown much. I wish you the best!

Thanks for using Petco Pet Education Center, formerly Petcoach! Possibilities include mast cell tumor, soft tissue sarcoma, plasmacytoma, carcinoma, something of a benign origin, among many others. It should be something similar or the same as the FNA. Ultimately, the biopsy is what actually provides the definitive diagnosis. Feel free to contact us back once the results are available and we can try to guide you going forward the best we can. Let's keep our fingers crossed that it is something benign. Good luck and have a great day!

Melanoma that is found in the toes has more potential to be malignant, but this is not a definite. One thing that's in Ada's favor is that she is a Miniature Schnauzer. About 75% of melanomas in this breed are benign, which decreases the likelihood of malignancy. The biopsy results should give some indication of malignancy, so I'd double-check with the vet that gave you the results. Staging of tumors requires that a veterinarian takes samples from nearby lymph nodes and takes x-rays. If this hasn't been done, then you can ask your veterinarian if this is necessary. The prognosis will depend on the grading and staging of the tumor, so I cannot comment about that at this time. I hope this helps and all turns out OK with Ada.