My 12-year-old dog has a fatty leg mass. Is a biopsy needed?

Needle aspiration of lipomas typically yields identifiable fat so i agree with your family vet that it is concerning to not have any material recovered with the needle aspirate. We always start with needle aspiration as it is non invasive with quick results but some masses are harder to diagnose with this test. This typically occurs if the mass is firmer in nature. Going to see a specialist can be helpful as we can sometimes use other techniques such as ultrasound to obtain samples with needle aspiration to try to avoid biopsy. But ultimately biopsy may be necessary for some masses. I hope this helps and thank you for using Petco Pet Education Center, formerly Petcoach!

Without a physical exam or diagnostics, it is difficult to determine if this is something to worry over. Ideally, a fine needle aspirate or biopsy should be done to collect samples for pathology. This may provide a diagnosis. X-rays of the limb may be recommended to rule out bony involvement. Since you state it is growing, it should be removed before it becomes too large. As it is, that is a difficult area to close after a mass removal.

Looking at the photo and considering your description of the progression of this, I would suspect that it is a growing mass. It could simply be a fatty lump such as a lipoma. Other possibilities would be a soft tissue swelling due to trauma, but this seems less likely considering the progression. I would head to the vet and get them to test the lump to see exactly what it is. If it is just a lipoma and not causing bother it should not need to be removed.

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!

Thank you for providing a picture of Mia's lump! It could be a benign tumor, a cyst, or a malignant tumor. Unfortunately in a senior dog, there is always a chance it could be malignant. Any suspicious lumps should be examined by the vet. The vet can perform a test called a fine needle aspirate on it. To do this, the vet sticks a small needle into the lump to get a sample of it's cells, and examines the cells on a slide under a microscope. It's usually painless to the animal, and relatively quick to perform. I would take her into the vet in the next couple of days to have this lump examined and diagnosed so it can be treated as needed. Good luck, I hope this helps!

Thanks for using Petco Pet Education Center, formerly Petcoach! This could be a benign or malignant growth. Given the fact that it is growing quickly, a malignant tumor is more likely. This is often differentiated by a test called a fine needle aspirate (FNA) which is a pain free, inexpensive and easy procedure which in most cases will help reach a diagnosis. Sometimes a biopsy is needed for a definitive diagnosis. I recommend that you have her evaluated by your veterinarian for further assessment and treatment. I am really hoping for something benign. Good luck and have a good day!

Osteosarcoma is typically a very aggressive cancer so it would be unusual for the pet to be doing well one and a half years later. There are many types of skin masses including benign bone growth. I recommend to play it safe and to have the mass aspirated by your veterinarian. This will give you a better idea of what’s going on and if it’s something that will cause a problem in the future or requires treatment. I hope this helps.