Dear Dr. John,
Not too long ago, I noticed a substantially sized growth on my cat’s underside. I adopted her from a shelter about 13 years ago as an adult cat. She was spayed at the shelter before I got her. When my vet showed me the growth more closely, it looked like she had a large fluid filled distended nipple. The vet recommended it be removed suggesting that it could be a cancerous growth. Could it be breast cancer or something else? The weird thing is she is scheduled to have it removed next week and the overall size of the swelling in the area is much smaller. Should I still proceed with the scheduled surgery? Why would a cancerous growth suddenly shrink? I’m also inclined not to have a biopsy done since she is so old, and it costs a lot. A.H.
Dear A.H.,
One can never say whether a growth is cancerous or not unless a biopsy is done. Often, veterinarians might consider doing a fine needle aspirate first in which a few cells are obtained by needle from a growth and examined to see if cancer is present or not. Based on the history you give; it appears that the cat may have been spayed as a young adult so breast adenocarcinoma is surely a possibility but the fact that the nipple appeared as it was, and the growth underneath shrunk in size suggests to me that your cat may have a cystic breast condition that may not be cancerous or a mixed tissue mass.
Cystic tissue sometimes gets smaller, and I cannot help but wonder if fluid leaked out of the nipple to allow the size to be reduced. I would suggest you proceed with the removal of the affected tissues and then have the biopsy done.
Depending on the result, you may decide to proceed with an oncology referral if necessary and subsequent chemotherapy or radiation. I would also ask about a preliminary chest radiograph to make sure that there is no sign of metastasis to the lungs since that is the most common location for that to happen. Hopefully, the removal of the growth and proper diagnostics such as biopsy will yield favorable answers for you. Good luck.
Dr. John de Jong owns and operates the Boston Mobile Veterinary Clinic. He can be reached at 781-899-9994
