Cat Skin Growths: Lumps, Scaling, and When to Worry

Name: Cat Skin Growths: Lumps, Scaling, and When to Worry
Creator: Dr. Zubair Khalid

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-10-03

Most new cat skin growths turn out to be harmless, but some are tumors or infections that need treatment. The only way to know which is which is to have a veterinarian look at the lump, scaling, or sore and often sample it. This article is educational and is not a substitute for veterinary diagnosis or treatment.

Quick Answer

Any new lump, bump, scab, or bald patch on your cat should be checked by a veterinarian, because skin tumors can look like harmless bumps and harmless bumps can look like tumors [1].
Tumors of the skin and the tissue just under it are the most common tumors seen in cats, partly because they are easy to see and the skin is constantly exposed to things that can cause tumors [1].
A growth that is growing fast, bleeding, ulcerated, painful, or changing color needs to be seen sooner, not watched at home.
Cauliflower-like or crusty growths are often warts, papillomas, or other benign growths, but some skin cancers can also look cauliflower-like, so sampling is the only way to tell.
Scaly, crusty, or ulcerated skin on the face, nose, or limbs can be caused by feline herpesvirus dermatitis, which is treatable but needs a diagnosis [2][3].

What Cat Skin Growths Look Like and What Is Normal

Cats normally have some lumps and bumps that are not tumors. A lipoma is a soft, movable fat lump under the skin. A sebaceous cyst is a small, round bump that may drain a cheesy material. A healing scab or a small callus on a pressure point is also normal. These are common and usually harmless.

What is not normal is a new growth that keeps changing. Skin tumors can appear as small lumps or bumps, but they can also show up as hairless areas, discolored patches, rashes, or sores that will not heal [1]. Because skin tumors are so diverse, telling a tumor apart from an inflammatory disease is difficult, and identifying a growth should be left to a veterinarian [1].

Some cats also get scaling and crusting without a true lump. Scaling can be dry and flaky, or it can be thick and greasy. It can be caused by allergies, parasites, fungal infections, or immune problems. In some cats, ulcerative and crusting lesions on the nose, face, or limbs are linked to felid alphaherpesvirus 1 infection [2][3].

If you are not sure whether a bump is new or old, take a photo with a ruler next to it and check it again in two weeks. Comparing photos is one of the most useful things you can do at home.

Main Causes of Cat Skin Growths

The table below groups the most common causes by what they usually look like and how quickly you should act.

Cause	Typical clues	How urgent
Benign skin tumors (basal cell tumors, papillomas, cysts)	Small, slow-growing, often hairless or cauliflower-like, not painful	Routine visit within a few weeks
Malignant skin tumors (basal cell carcinoma, squamous cell carcinoma, mast cell tumor)	Firm, fast-growing, ulcerated, bleeding, or changing color	See a vet within days
Mast cell tumor	Raised lump, may wax and wane in size, can be itchy or red	See a vet within days
Feline herpesvirus dermatitis	Crusting, ulceration, often on nose, face, or limbs, sometimes with pain	See a vet within days
Plasma cell neoplasia	Multiple lumps, often in lymph nodes or under the skin, may spread	See a vet promptly
Vascular proliferation (angiomatosis)	Purple, depressed lesion, often on a paw pad, may ulcerate and hurt	See a vet within days
Paraneoplastic alopecia	Hair loss on the belly and legs with shiny skin, linked to an internal tumor	See a vet promptly
Allergies, parasites, fungal infections	Scaling, redness, itching, often seasonal or after contact with other animals	Routine visit

Benign Growths

Basal cells sit at the base of the top layer of skin. A benign growth of these cells is a basal cell tumor, and a malignant growth is a basal cell carcinoma [1]. Benign basal cell tumors are common in cats and usually grow slowly. Papillomas and warts can look cauliflower-like. Sebaceous cysts and lipomas are also common and usually harmless.

Malignant Growths

Malignant skin tumors in cats include squamous cell carcinoma, basal cell carcinoma, and mast cell tumors. A mast cell tumor is a tumor of the immune cells that live in the skin. One report described a mast cell tumor in a cat that was a poorly defined mass in the skin of the inner thigh, made of abnormal mast cells [4]. Mast cell tumors can be itchy and can change size from day to day, which is why owners sometimes think a lump has come and gone.

Growths Linked to Internal Disease

Some skin signs point to a problem inside the body. Feline paraneoplastic alopecia is hair loss linked to tumors inside the abdomen. One report described a cat with a skin mass on the head followed by hair loss on the belly and legs with shiny skin, and the cat was found to have an apocrine adenocarcinoma [5]. This is uncommon, but it is a reason not to ignore widespread hair loss with shiny skin.

Plasma cell neoplasia is another uncommon cancer in cats. One report described a cat with a multicentric round cell cancer with plasma cell features that responded to radiation and chemotherapy [6]. This shows that even uncommon skin and lymph node cancers can be treated.

Infections and Other Causes

Feline herpesvirus dermatitis causes ulcerative and crusting lesions, often on the nose, and can also affect the flank, elbow, shoulder, or tarsal area [2]. An atypical case in a cat had lesions on the limbs and shoulder without any facial or oral involvement [3]. This means herpesvirus dermatitis can show up in places you might not expect.

A rare non-cancerous vascular growth called angiomatosis can appear as a purple, depressed lesion on a paw pad that ulcerates and causes pain [7]. It is not a tumor, but it still needs a diagnosis and treatment.

Red Flags That Make It an Emergency

Call your veterinarian right away or go to an emergency clinic if you see any of these:

A growth that is bleeding heavily and will not stop.
A growth that has suddenly doubled in size over a few days.
A sore that is deep, open, and draining pus or foul-smelling fluid.
Your cat is limping, crying, or pulling away when you touch the area.
Your cat is not eating, is hiding, or seems painful.
A growth on the eyelid, nose, mouth, or paw pad that is affecting eating, breathing, or walking.
Sudden widespread hair loss with shiny skin, especially on the belly and legs [5].

These signs do not always mean cancer, but they mean your cat needs to be seen now.

What You Can Do at Home While You Wait

You cannot diagnose a growth at home, but you can keep your cat comfortable and gather useful information.

Take clear photos of the growth with a ruler or coin next to it for scale. Take photos from a few angles.
Measure the growth with a soft tape measure and write down the size and date.
Do not squeeze, pick at, or try to pop the growth. This can cause bleeding, infection, or spread of abnormal cells.
Do not apply human creams, ointments, or essential oils to the growth. Cats groom themselves and can swallow products that are toxic to them.
Keep your cat indoors and away from other animals if the growth is open or crusty.
Note any changes in appetite, energy, drinking, or litter box habits.
If your cat is scratching at the growth, ask your veterinarian about a cone or a safe cover until the visit.

If you are deciding whether a lump needs a visit, this guide on cat skin bumps and lumps and when to see a vet can help you sort out what to watch.

What the Veterinarian Will Check and Test

Your veterinarian will start with a full physical exam. They will feel the growth, measure it, and check the surrounding skin, lymph nodes, and the rest of your cat's body. They will ask when you first noticed it and whether it has changed.

Common Tests

Fine needle aspiration: a thin needle is used to collect cells from the growth. The cells are placed on a slide and looked at under a microscope. This is quick, usually well tolerated, and often gives an answer the same day.
Biopsy: a piece of the growth is removed and sent to a lab. This gives the most detailed information and can tell benign from malignant.
Skin scraping or cytology: used when scaling, crusting, or infection is the main problem.
Fungal culture or PCR testing: used if a fungal infection or herpesvirus is suspected [2][3].
Blood work and imaging: used if the veterinarian suspects a tumor has spread or if there is widespread hair loss that could be linked to an internal tumor [5][6].

What Treatment Might Look Like

Treatment depends on the diagnosis. Benign growths may be monitored or removed. Some skin cancers are removed surgically. Radiation and chemotherapy are used for some cancers, and one report described a cat with plasma cell neoplasia that had complete resolution on imaging after radiation plus chemotherapy [6]. A topical beta-blocker was used successfully to prevent recurrence of ulceration in a cat with a vascular paw pad lesion [7]. Your veterinarian will calculate any dose based on your cat's weight and health.

If cost is a concern, this article on what the vet will do and how much it costs walks through the typical steps.

Prevention and Monitoring

You cannot prevent every skin growth, but you can lower some risks and catch problems early.

Keep your cat indoors. This reduces sun exposure and contact with other animals that can spread viruses and parasites.
Use sun protection for light-colored cats with thin fur on the ears and nose if they spend time in sunny windows.
Check your cat's skin once a month. Run your hands over the whole body, including the belly, legs, paw pads, and behind the ears.
Keep a simple log of any lump with its size and date. Update it every month.
Treat skin infections and allergies promptly so the skin barrier stays healthy.
Keep up with routine veterinary visits, especially as your cat gets older.

If your cat has a rash with swelling or bumps, this guide on cat skin rash with swelling and this one on cat skin rash with bumps can help you tell a skin allergy from a growth.

Limitations and When to Contact a Veterinarian

No article can tell you what a specific growth is. Only a veterinarian who examines your cat and possibly samples the growth can do that. Individual cases need a veterinarian.

Contact your veterinarian the same day if you see a new growth that is growing, bleeding, ulcerated, or painful, or if your cat is licking or chewing at it. Go to an emergency clinic now if there is heavy bleeding, a deep open wound, trouble breathing, or severe pain. Schedule a routine visit within a few weeks if you find a small, stable, non-painful lump or patch of scaling that has not changed.

Frequently Asked Questions

What does a cauliflower-like growth on my cat mean?

A cauliflower-like growth is often a benign papilloma or wart, but some skin cancers can also have that texture. The only way to know is to have your veterinarian sample it with a fine needle or biopsy. Do not try to remove it at home.

Is scaling on my cat's skin always a sign of cancer?

No, scaling is much more often caused by allergies, parasites, dry skin, or infections. Some cats with herpesvirus dermatitis get crusting and ulceration on the nose, face, or limbs [2][3]. A veterinarian can tell the difference with an exam and simple tests.

Can a cat skin lump go away on its own?

Some lumps, like cysts or insect bites, can shrink or go away. Mast cell tumors can also change size, which makes them look like they are going away when they are not. Any lump that stays for more than a few weeks or changes should be checked.

Should I put ointment on my cat's skin growth?

No. Human ointments and creams can be toxic to cats if they lick them off. Keep the area clean and dry, and ask your veterinarian before applying anything. If the growth is open, cover it only if your veterinarian tells you to.

How often should I check my cat for new growths?

Once a month is a good routine for most adult cats. Check more often if your cat has had a skin tumor before or is older. Measure any new lump and write down the date so you can tell your veterinarian whether it is growing.

References

Tumors of the Skin in Cats - Cat Owners. Merck Veterinary Manual.
Dermal inflammatory vascular changes associated with felid alphaherpesvirus 1 dermatitis in cats. Journal of comparative pathology, 2026.
Atypical felid alphaherpesvirus 1 dermatitis in a cat. Journal of veterinary diagnostic investigation : official publication of the American Association of Veterinary Laboratory Diagnosticians, Inc, 2026.
Feline cutaneous mast cell tumor with extensive macrophage-associated cell-in-cell structures. Journal of veterinary diagnostic investigation : official publication of the American Association of Veterinary Laboratory Diagnosticians, Inc, 2026.
Putative paraneoplastic alopecia in a cat with apocrine adenocarcinoma. Veterinary dermatology, 2025.
Multicentric Round Cell Neoplasia with Plasmacytic Differentiation in a Cat with Systemic Progression: Multimodal Imaging and Treatment Response. Animals : an open access journal from MDPI, 2026.
A Case of Slow Progressive Cutaneous Angiomatosis on a Cat Metatarsal Pad Treated by a Topical Beta-Blocker. Veterinary dermatology, 2026.