Cat Skin Nodules and Ear Nodules: What to Do

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

A cat skin nodule is a solid bump you can feel under or on the skin, and it may be harmless or a sign of cancer. The same is true for lumps on or inside the ears. Because you cannot tell the difference by touch alone, a veterinarian needs to examine any new or changing nodule.

This article is educational and is not a substitute for veterinary diagnosis or treatment.

Quick Answer

• Skin tumors are the most commonly seen tumors in cats, partly because they are easy to see and the skin is constantly exposed to tumor-causing factors in the environment [1].
• Ear canal tumors in cats are more often malignant than benign, especially after age 11 [2].
• A nodule that grows quickly, bleeds, drains, smells bad, or sits inside the ear canal needs prompt veterinary attention [2].
• Do not squeeze, poke, or try to remove a nodule at home. You can keep the area clean and note changes in size and appearance.
• Your veterinarian will likely recommend a fine needle sample or biopsy, because the only way to know what a nodule is involves looking at the cells [1][3].

What a Cat Skin Nodule or Ear Lump Looks Like

A nodule is a solid, raised bump. It can be small like a pea or large like a marble. Some sit on top of the skin. Others sit in the tissue just under the skin, so you feel them more than you see them. Tumors affecting the skin or the tissue just under the skin are the most commonly seen tumors in cats [1].

Normal skin has some bumps that are not tumors. These include insect bites, cysts, and reactions to a scratch. Cats also get harmless skin tags and waxy plugs in the ear. A normal ear canal is pale pink and mostly clean, with a small amount of light wax.

What matters is change. A lump that stays the same size for months is less worrying than one that doubles in a few weeks. A lump that was never there before deserves a look.

Ear nodules are easy to miss because they sit inside the canal. You may notice instead that your cat shakes its head, scratches one ear, or has discharge from one side. Signs of an ear canal tumor include ongoing discharge that can be waxy, pus-filled, or bloody, a foul odor, head shaking, scratching, swelling, draining abscesses below the ear, or deafness [2]. If the middle or inner ear is involved, you may see loss of balance, a head tilt, or neurological signs [2].

If your cat is scratching its ears raw, that is a separate problem that also needs care. You can read about it in Cat Scratching Its Ears Raw: What to Do Right Now.

Main Causes of Nodules on Cats

Many things cause nodules. Chemical carcinogens, solar radiation, and viruses can all cause skin tumors, and hormonal and genetic factors may play a role too [1].

Here is a practical table of common causes and what makes each one stand out.

Skin Tumors and Cancer

Tumors are abnormal growths of cells [1]. Some are benign, meaning they do not spread. Others are malignant, meaning they grow fast or spread to other parts of the body.

Lymphoma is a cancer of the blood and lymphatic system. A rare form can first appear as lymphoid infiltrations of the skin, causing distinctive tumors. In most cats, lymphoma begins elsewhere, such as the intestinal tract or the lymphatic system, and can occasionally spread to the skin. Lymphoma is associated with infection by feline leukemia virus. There are two forms of skin lymphoma, epitheliotropic and nonepitheliotropic [1].

Ear Canal Tumors

Ear canal tumors can arise from skin, earwax and oil glands, bone, connective tissue, muscle, or deeper skin layers. Tumors of the external canal and outer ear are more common than those of the middle or inner ear. Malignant ear canal tumors are more common in cats than in dogs, although they are less common than other skin tumors [2].

Long-term ear canal inflammation can lead to abnormal tissue growth and, eventually, tumors. Bacterial infections that increase earwax production might also promote cancerous changes [2]. This is one reason chronic ear problems should not be left untreated. If your cat has a long-standing ear infection, see How To Treat Cat Ear Infection.

One reported case described a 9-year-old cat with inflammatory discharge and a polypoid mass in the left ear canal that penetrated the eardrum. The mass was removed but not sent for testing at first. Imaging later showed an irregular mass in the tympanic bulla, and surgery confirmed a tympanic papillary adenoma. The tumor recurred within 17 months [4]. This case shows why follow-up matters even after a mass is removed.

Infections and Other Causes

Not every nodule is a tumor. A 4-year-old cat was referred with 8 months of chronic, non-healing draining wounds on the thigh and groin after a bite wound. Cytology of a groin mass suggested a spindle cell tumor, but histopathology after surgery showed severe inflammation and no cancer. Bacterial culture grew Mycobacterium farcinogenes. The cat was treated with pradofloxacin, topical amikacin gel, and azithromycin and went into complete remission after 24 weeks [3]. The exact drug doses are not given here because your veterinarian calculates doses from your cat's weight and health.

This case matters for owners because it shows that a lump can look like cancer on one test and turn out to be an infection. It also shows that draining wounds that do not heal need deeper testing.

Cat scratch disease is another infection linked to cats. It is caused by Bartonella henselae and spreads mainly through scratches or bites from infected cats, especially kittens. The hallmark is a papule or pustule at the inoculation site followed by tender swollen lymph nodes nearby, often with low-grade fever [5]. In people, it often resolves on its own in 2 to 4 weeks, but more severe forms can occur [5].

Some lumps are not skin problems at all. A 7-year-old cat with vomiting, poor appetite, and abdominal swelling had a very large cystic liver mass that turned out to be a hepatobiliary cystadenoma, a benign biliary tumor [6]. Another report described thymoma, the second most common mediastinal tumor in cats, treated with surgery [7]. These are internal masses, but they remind you that a lump you feel on the belly wall may not be the whole story.

Red Flags That Mean Emergency or Same-Day Care

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

• A nodule that is bleeding heavily or will not stop bleeding
• A lump that ruptured and is draining pus or blood
• Sudden swelling around the ear or face with pain when you touch it
• Loss of balance, head tilt, or stumbling, which can mean the middle or inner ear is affected [2]
• Trouble breathing, collapse, or severe lethargy
• A mass that appeared or grew very fast over days

For non-emergency but urgent concerns, such as one-sided ear discharge that has not improved with treatment, book a visit within a few days. Persistent one-sided inflammation that does not respond to treatment raises concern for a tumor [2].

If you see blood in the ear discharge, that also needs a prompt exam. See Cat Ear Infection with Blood: What to Do Right Now.

What You Can Safely Do at Home While Waiting

You cannot diagnose or treat a nodule at home. What you can do is gather good information and keep your cat comfortable.

• Take photos with a ruler or coin next to the lump so you can track size.
• Write down when you first noticed it and whether it has changed.
• Note any discharge, odor, bleeding, or scratching.
• Keep the area clean with a damp cloth if it is dirty. Do not use human creams, peroxide, or alcohol on it.
• Do not squeeze, lance, or try to pull off a nodule. This can cause bleeding, infection, or spread of abnormal cells.
• Use a cone if your cat is scratching or chewing at the spot.
• Keep your cat indoors so you can monitor it and reduce sun exposure to light-colored ear tips and noses.

If your cat has hair loss on the ears along with a lump, that combination has its own list of causes. See Cat Hair Loss on Ears: Causes and What to Do.

What Your Veterinarian Will Check and Test

Your veterinarian will start with a full physical exam, including the ears, lymph nodes, and mouth. They will measure the nodule and check whether it is movable or fixed to deeper tissue.

Common Tests

• Fine needle aspiration: a thin needle collects cells from the lump. This is quick and often done in the exam room.
• Biopsy or histopathology: a tissue sample is sent to a lab. This is the only way to confirm what a mass is. In the mycobacteriosis case, cytology suggested a tumor but histopathology showed infection instead [3].
• Ear exam and imaging: if a mass is inside the ear canal, your vet may use an otoscope and recommend imaging such as CT to see the middle ear [4].
• Blood work: this checks overall health and can support suspicion of lymphoma linked to feline leukemia virus [1].
• Cultures: if a wound is draining and not healing, bacterial culture can identify organisms like Mycobacterium [3].

Treatment depends on the diagnosis. Benign lumps may be monitored or removed. Malignant tumors may need surgery, and some need other treatments that your veterinarian will discuss. Ear canal surgery can be complex, and in one reported case the tumor recurred after 17 months, so follow-up exams are part of the plan [4].

Prevention and Monitoring

You cannot prevent every nodule. You can lower some risks and catch problems early.

• Do a monthly nose-to-tail check. Run your hands over your cat's body, including the ears, armpits, belly, and legs.
• Feel inside the ear flap and look into the canal opening with a light.
• Treat ear infections promptly. Long-term inflammation can lead to abnormal tissue growth and tumors [2].
• Limit sun exposure for light-colored cats, since solar radiation can cause skin tumors [1].
• Keep up with flea control, since fleas spread Bartonella among cats [5].
• Keep your cat's leukemia virus status current with your veterinarian, since lymphoma is associated with feline leukemia virus infection [1].
• Ask your vet to recheck any lump that was previously sampled, even if it seemed harmless.

If you find a new bump and are not sure whether it needs a visit, this guide can help you decide: Cat Skin Bumps and Lumps: When to See a Vet and When to Monitor.

Limitations and When to Contact a Veterinarian

No article can tell you what a specific lump is. Only your veterinarian can examine your cat, sample the nodule, and give you a diagnosis. Individual cases need a veterinarian.

Contact your veterinarian the same day if a nodule is bleeding, draining, painful, or growing fast. Go to an emergency clinic now if your cat has trouble breathing, collapses, has sudden balance loss or a head tilt, or has a mass that ruptured and will not stop bleeding [2].

Book a routine visit within a week or two if you find a new nodule that is small, stable, and not bothering your cat. Book sooner, within a few days, if the nodule is inside the ear canal, if there is one-sided discharge or odor, or if your cat is shaking its head or scratching one ear [2].

Frequently Asked Questions

Can a cat skin nodule go away on its own?

Some nodules do go away, especially ones caused by insect bites, minor trauma, or short-term infections. Others, including tumors, will not resolve without treatment. Because you cannot tell which is which by looking, have any nodule checked if it lasts more than a couple of weeks or changes in any way.

Are ear nodules in cats usually cancer?

Ear canal tumors in cats are more often malignant than benign, especially after age 11 [2]. That said, not every ear lump is a tumor. Inflammatory polyps and infections can also cause masses in the canal. A veterinary exam and often a tissue sample are needed to know which one your cat has.

How does a veterinarian tell if a lump is benign or malignant?

The main method is sampling the tissue. A fine needle aspiration collects cells for a quick look, and a biopsy gives a full tissue diagnosis. In one reported case, cytology suggested a tumor but histopathology showed an infection instead [3]. This is why lab testing matters more than appearance alone.

Should I worry about a small lump on my cat's ear?

Size alone does not tell you whether a lump is safe. A small nodule inside the ear canal can cause big problems, including discharge, odor, and hearing loss [2]. A small lump on the ear flap is easier to watch, but if it grows, bleeds, or changes color, have it checked.

Can cat scratches cause lumps in people?

Yes. Cat scratch disease is caused by Bartonella henselae and spreads mainly through scratches or bites from infected cats, especially kittens. It usually causes a small bump at the scratch site followed by swollen, tender lymph nodes nearby, often with low-grade fever [5]. See a doctor if you develop these signs after a scratch or bite.

Related Articles

• Cat Hair Loss on Ears: Causes and What to Do
• How To Treat Cat Ear Infection
• Cat Scratching Its Ears Raw: What to Do Right Now
• Cat Ear Infection with Blood: What to Do Right Now
• Cat Skin Bumps and Lumps: When to See a Vet and When to Monitor
• Cat Scratching Their Ears
• Lump or Growth on Your Cat's Ear: Causes and Next Steps
• Cat Ear Zit or Bump: Causes and When to Worry
• Cancer in a Cat's Ear: Tumors and Warning Signs

References

1. Tumors of the Skin in Cats - Cat Owners. Merck Veterinary Manual.
2. Tumors of the Ear Canal in Cats - Cat Owners. Merck Veterinary Manual.
3. Feline Cutaneous Mycobacteriosis Caused by Mycobacterium farcinogenes: The First Case Report from Asia. Animals : an open access journal from MDPI, 2026.
4. Tympanic papillary adenoma (tympanic papilloma) in a cat - a case report. Journal of comparative pathology, 2026.
5. Cat Scratch Disease. 2025.
6. Giant Hepatobiliary Cystadenoma Requiring Biliary Reconstruction in a Cat: A Case Report. Veterinary medicine and science, 2026.
7. Evaluation of intercostal thoracotomy as a surgical approach for feline thymoma: A case series of seven cats. Open veterinary journal, 2026.

Further Reading

• Merck Veterinary Manual: Cat Owners
• Cornell Feline Health Center: Health Information
• American Veterinary Medical Association: Pet Care