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My puppy has a growing red lump. Is it a histiocytoma or cancer?

Updated On September 23rd, 2025

Pet's info: Dog | Staffordshire Bull Terrier | Male | unneutered | 7 months and 9 days old | 26.5 lbs

Hi, my 8 month old Staffordshire Bull Terrier has started developing a red lump around 3 weeks ago. It started off as a pea-sized lump when I first noticed it, and has then developed into a significantly wider growth. The first picture attached is a week after the growth was noticed, the second picture is a week after that and the third is from today, 3 or so weeks after finding it. The vet believes it could be a histiocytoma and has suggested waiting for 2-3 months to see if it goes away?

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3 Answers

Most Helpful Answer

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Answered By Dr. Elizabeth

Veterinarian

Published on September 10th, 2019

Your vet is correct that the most likely diagnosis is a histiocytoma. However, another serious cancer called a Mast Cell Tumor can also look like this and can (although more rare) appear on young dogs. Aspirating the mass is easy, doesn't require sedation or stitches and will generally give you the correct diagnosis. I recommend to discuss this option with your vet to know if this is something to worry about. I hope this helps and please feel free to post any additional questions.

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3Pet Parents found this answer helpful

Other Answers

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    Answered By Dr. Elizabeth

    Veterinarian

    Published on January 17th, 2024

    Hello! I'm happy to help and I certainly understand your concern. When pets get red, raised hairless masses like this one on Piper, I do recommend to have them examined. Most of the time, masses that look like this are something benign like a Histiocytoma. Rarely, a mass like this can be a cancerous tumor called a Mast Cell Tumor. It's best to have the mass tested (which is quick and easy as long as Piper will hold still) so that you can be assured it's nothing that needs any type of treatment. I recommend to have her examined in the next week or so. If Piper is licking at the mass, I do recommend to have her wear an Elizabethan collar to prevent licking. Licking will make the mass more itchy and can cause a secondary infection. I hope this helps and that things get figured out quickly. Please feel free to check in anytime. Sincerely, Dr. Elizabeth

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    1Pet Parents found this answer helpful

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    Answered By Laura Johnson VMD

    Veterinarian

    Published on August 20th, 2017

    Hi, thanks for using Petco Pet Education Center, formerly Petcoach! Many different skin bumps can look very similar. The 2 most common bumps that look like that, red, raised and hairless, are: histiocytomas which are benign and are common in young dogs. They usually spontaneously regress in 1-2 months. So it's been a bit longer than normal. The other is a Mast Cell Tumor. The 2 are easily distinguished by aspiration of the lump and sending slides out to the lab to have a pathologist review them. There are other types of masses too it could be. Since it has been there for 2 months I recommend having your Vet discuss either aspirating it or removing it for biopsy. I hope this helps and good luck!

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