Cat Skin Lumps, Bumps, and Cysts

By Katie Grzyb, DVM. Reviewed by Brittany Kleszynski, DVM

Updated Aug. 28, 2024

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Malignant vs. Benign Lumps on Cats

Masses on cats can be either benign or malignant.

Benign masses are defined as tumors that don’t spread, or metastasize, to other areas of the body. Usually, benign masses don’t have invasive characteristics, while malignant (or cancerous) tumors can attack the surrounding tissue or spread.

Benign masses typically require little to no therapy.

Speedy diagnosis and treatment of malignant tumors is necessary to give your cat the longest and best quality of life possible.

If you are concerned about abnormal skin lumps on your cat, contact your veterinarian so they can provide a thorough physical examination and offer diagnostic testing.

Types of Lumps and Bumps on Cats

Some common causes of benign tumors in cats may include:

Trauma: If a cat bumps a part of their body, lumps or firm bruises can form in these areas. These types of bumps on a cat’s skin usually go away in less than a week.
Insect/parasite bites: Insect and parasite bites often show up as red, raised bumps on a cat’s skin and frequently cause irritation and/or itching.
- You may see fleas in the area, or a tick feeding on the skin. If you find a tick on your cat, it’s critical to remove it promptly and carefully to reduce the risk of tick-borne diseases, such as Lyme disease.
- A veterinarian can assist with this task if you need guidance to ensure all parts of the tick are removed. Spider bites and ant bites look like flea and tick bites. These red bumps usually go away within a few days.
Allergic reaction/anaphylaxis: Some environmental irritants, such as foods or insect bites, can cause hives, which cause itchy bumps on a cat’s skin that can be flattened or raised and sometimes reddened. If your cat is having an allergic reaction, contact your vet immediately.
Skin tags: Cat skin tags are benign overgrowths of skin cells that can pop up anywhere on the body. Usually, these are small and do not bother cats. Cat skin tags grow quickly and usually don’t change color unless they’re irritated.
Abscesses: An abscess is an infection within tissue. The infection develops under a healed wound, and this prevents the infected fluid (or pus) from draining. Abscesses are often associated with puncture wounds, such as animal bites or scratches, and they can be found anywhere on a cat’s body.
Cysts: Cat cysts are benign masses that often contain fluid or thicker, non-infected material. They are usually raised and can be round or oval, firm or soft. Cat cysts are usually not painful, but they can get inflamed or infected over time, especially if your cat is licking the area consistently.
Granulomas: These areas of chronic inflammation form a solid mass that is often gritty in consistency. Granulomas can appear as small, raised, well-delineated masses on cats or as red, raised, ulcerated areas of skin that can have a “ground glass” appearance.
- Cats can develop eosinophilic granuloma complex (EGC), a condition that makes them prone to granulomas.
Lipomas: Cat lipomas are benign fatty tissue growths that are usually felt under the skin around the abdomen, flank, or neck of a cat. They tend to grow underneath a cat’s skin, and are slow-growing, non-painful tumors. Surgical removal may be recommended by your veterinarian.
Warts: Warts on cats are benign bumps on a cat’s skin. Warts (also called papillomas) are caused by papillomavirus and are rare in cats.
Horned paw: These benign growths—also called cutaneous horns—are often thin and horn-like and show up in a cat’s paw pads. They are caused by keratin overgrowth within the skin, like a callus formation in humans.
Acne: Cats are prone to feline acne. These bumps on a cat’s skin typically develop around the lips, chin, and/or face. Like humans, cat acne is caused by oils clogging the pores. Cat acne can be due to allergies and/or genetics.
Pyoderma: Pyoderma in cats is a type of skin infection caused by bacteria or yeast. This causes tiny, red, raised bumps on a cat’s skin.
- This condition is rare in cats, but it can progressively get worse if it’s left untreated.

Some common types of malignant tumors in cats include:

Basal cell tumors: Basal cell tumors in cats are the most common type of skin tumor in cats and are usually found in middle-aged and older cats. Basal cell tumors are small, firm masses most seen around a cat’s head and neck.
Squamous cell carcinomas: These malignant lumps on cats are usually seen in middle-aged and older felines. They’re found in areas with little hair or skin pigmentation, usually around the head, ears, nose, and mouth. Squamous cell carcinomas in cats don’t often spread through the body, but they tend to quickly grow into the skin surrounding the original tumor.
Mast cell tumors: Mast cell tumors in cats are most commonly found around a cat’s head and neck, but they can invade any part of the body. They can spread to organs such as the liver or spleen, and even the bone marrow.
Fibrosarcomas: These aggressive tumors often affect the limbs or between the shoulder blades in middle-aged and senior cats. They typically do not spread to distant organs but are locally invasive.

Like humans, veterinarians believe tumors develop because cats are often exposed to tumor-causing environmental factors.

These factors include UV radiation, viruses, and chemical pollutants.

Tumors can also be caused by genetic or hormonal issues.

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What To Do if You Find a Lump or Bump on Your Cat

If you find a bump on your cat’s skin, schedule an appointment with your veterinarian.

They’ll be able to investigate the cause and decide whether the mass could become a larger issue or needs immediate treatment.

How Vets Diagnose Lumps and Bumps on Cats

To diagnose a bump on a cat’s skin, your veterinarian will likely identify the mass by color, size, consistency, and movement (growing into the underlying tissue or only felt on the skin).

Often, a fine needle aspirate (FNA) and cytology will be performed.

During an FNA, a small needle is used to obtain a sample of cells from the mass, which are then sent to a laboratory for assessment. With some cat cysts and bumps it’s easy to diagnose them using this test alone.

Sometimes, a surgical biopsy to remove a portion of the mass (or the entire mass) may be done if the FNA was not diagnostic or if the veterinarian wants more information.

Biopsies can determine the type of mass and its severity, which can help veterinarians choose the most appropriate treatment.

Treatment for Lumps and Bumps on Cats

Treatment ranges from topical therapy and oral medications (such as steroids including prednisone and immunosuppressive medications including chlorambucil) to surgical removal of the mass.

Depending on the type of mass, further therapy with radiation and/or chemotherapy may be necessary, especially if the tumor is locally invasive or has spread to distant organs.

Your vet will determine a plan based on your cat’s health and diagnosis.