Histiocytoma in Cats: Do Cats Get These Skin Lumps?

Name: Histiocytoma in Cats: Do Cats Get These Skin Lumps?
Creator: Dr. Zubair Khalid

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

Do cats get histiocytomas? The short answer is rarely, and true cutaneous histiocytoma in cats is not the same disease that dogs get. Histiocytic disorders do occur in cats, but they are uncommon and often look different from the classic benign button tumor seen in young dogs [1]. If your cat has a new skin lump, the lump itself matters more than the label, so a veterinary exam is the first step.

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

Quick Answer

True cutaneous histiocytoma, the benign lump that young dogs get and that often fades on its own, is a dog disease. Langerhans cell disorders of this type do not occur in feline skin [1].
Cats can develop other histiocytic tumors, including histiocytic sarcoma, which is aggressive and can spread to organs such as the spleen, lung, lymph nodes, and bone marrow [1].
A histiocytic tumor has been reported on a cat's toe, so these lumps can appear on the feet and cause lameness [2].
Most skin lumps in cats cannot be identified by look or feel alone. Fine needle aspiration or biopsy is needed for a diagnosis.
Any new, growing, bleeding, or painful lump deserves a veterinary visit. Early evaluation is simpler than waiting.

What Is a Histiocytoma in Cats?

A histiocytoma is a tumor made of histiocytes. Histiocytes are immune cells that normally help the body fight infection and clear debris. When these cells multiply out of control, they form a mass.

In dogs, the common version is called cutaneous histiocytoma. It comes from a type of histiocyte called a Langerhans cell, and it usually appears as a small, hairless, red lump on a young dog. These lumps often go away on their own as the immune system attacks them [3].

Cats are different. The Langerhans cell skin disorder that causes classic cutaneous histiocytoma in dogs does not occur in feline skin [1]. So when an owner asks whether their cat has a histiocytoma, the honest answer is that this exact tumor is not a recognized feline skin disease.

That does not mean cats have no histiocytic disease at all. Histiocytic proliferative disorders are seen in cats, just far less often than in dogs [1]. The most important one to know about is histiocytic sarcoma, a malignant tumor that starts in tissues throughout the body and can spread quickly [1]. There is also a rare lung condition called feline pulmonary Langerhans cell histiocytosis, which causes respiratory failure from diffuse histiocyte infiltration in the lungs [1][4].

Cutaneous Histiocytoma in Cats

When people search for cutaneous histiocytoma in cats, they usually mean a skin lump that a veterinarian might call a histiocytic tumor. These are uncommon in cats [1]. One documented case involved a granular variant of a histiocytic tumor on the toe of a 16-year-old cat that came in for lameness and a mass on a hind digit [2].

That case shows two useful points. First, histiocytic tumors in cats can show up on the feet, not only on the trunk or head. Second, a lump on a toe can cause limping, so lameness and a visible mass can go together [2].

Malignant Fibrous Histiocytoma in Cats

Malignant fibrous histiocytoma is a term that has been used for certain soft tissue tumors. It has been described uncommonly in dogs, including a splenic case in a dog that also had high blood pressure and nosebleeds [5]. There is no feline case in published veterinary research, so it is fair to say this tumor is not a well-documented feline skin problem. If a pathologist uses this term on your cat's biopsy report, ask your veterinarian to explain exactly what it means for your cat's case.

Histiocytoma in Cats Symptoms: What Owners Notice

Owners usually notice a lump before anything else. The signs depend on where the mass is and whether it is benign or malignant.

Common things you may see:

A new bump under the fur that was not there before
A lump that is hairless, red, or ulcerated on the surface
A mass that grows over days to weeks
Limping or reluctance to bear weight if the lump is on a paw or leg [2]
Licking, chewing, or sensitivity when you touch the area
Weight loss, poor appetite, or lethargy if a tumor is spreading internally [1]

Some skin tumors in cats look like harmless cysts or insect bites. Others look angry and raw. Appearance alone does not tell you whether a lump is benign. Basal cell tumors, for example, are benign in cats but can still grow fast and cause extensive ulceration and inflammation [6]. That is one reason a hands-on exam matters.

If you are unsure whether a bump needs a visit, this guide on cat skin bumps and lumps: when to see a vet and when to monitor can help you sort out what to watch and what to book.

Causes and Risk Factors

The cause of histiocytic tumors is not fully understood. These tumors come from immune cells, and their behavior ranges from harmless to aggressive [1].

Age plays a role in many feline skin tumors. Basal cell tumors are common in older cats, and basal cell carcinomas occur most often in aged cats [6]. Histiocytic disease in cats also tends to appear in mature to older animals, though the toe tumor case involved a 16-year-old cat [2].

Breed can matter for some skin tumors. Domestic longhair, Himalayan, and Persian cats are most at risk for basal cell tumors, and Persians are more prone to the malignant basal cell carcinoma form [6]. No specific breed predilection for feline histiocytic tumors stands out in the same way.

Sex does not appear to be a strong factor in cats based on what is known. In dogs, cutaneous histiocytoma cases are more common in males and in young dogs, but that pattern applies to dogs, not cats [3].

Sun exposure, viruses, and vaccines are often blamed by owners for lumps. For histiocytic tumors specifically, there is no clear evidence in these sources pointing to a single cause you can prevent.

How Veterinarians Diagnose a Skin Lump

Diagnosis starts with a physical exam. Your veterinarian will feel the lump, measure it, check the surrounding skin, and look for other masses. They will also check the lymph nodes and may listen to the chest.

The next step is usually a fine needle aspirate. A thin needle collects cells from the lump, and a pathologist or your vet examines them under a microscope. This is quick, inexpensive, and often gives a strong clue about what the lump is.

Sometimes cytology is not enough. A biopsy removes a piece of tissue or the whole lump so a pathologist can look at the cells and their arrangement. In the toe tumor case, the diagnosis was confirmed with histology and special staining that identified the tumor cells by markers including Iba1 and CD18 [2].

Tests Your Vet May Recommend

Test	What it does	When it is used
Fine needle aspirate	Collects cells for microscopic review	First step for most new lumps
Biopsy	Provides tissue for a full pathology report	When cytology is unclear or cancer is suspected
Blood work	Checks overall health before surgery or treatment	Before anesthesia or if illness is suspected
Imaging (X-rays, ultrasound)	Looks for spread inside the body	If a malignant tumor is possible

Imaging becomes important if a malignant histiocytic tumor is suspected, because histiocytic sarcomas can spread to the spleen, lung, lymph nodes, bone marrow, and other sites [1]. If your vet recommends an abdominal scan, this article explains what the images can show: abdominal ultrasound in cats: normal findings and common abnormalities.

Your veterinarian may also rule out look-alike conditions. A raised, hairless nodule on a cat's lip turned out to be feline leprosy caused by a mycobacterium, confirmed with cytology, histopathology, and PCR testing [7]. That case is a reminder that not every lump is a tumor, and infection can mimic one.

Treatment Options

Treatment depends on what the lump is, where it is, and whether it is benign or malignant.

Monitoring

If a lump is small, benign, and not bothering your cat, your veterinarian may suggest watching it and rechecking in a few weeks. Take a photo with a ruler next to the lump so you can track size changes accurately.

Surgical Removal

Surgery is the most common treatment for skin tumors in cats. Basal cell tumors are treated effectively with surgical removal, and the same is true for basal cell carcinomas, which spread to nearby skin but seldom to other organs [6]. Removing a lump also gives you a diagnosis, since the tissue goes to a pathologist.

For a toe or paw mass, surgery may be more involved because your cat needs that foot to walk. Your veterinarian will weigh the benefits of removal against function.

Other Treatments

If a tumor is malignant and has spread, or if surgery cannot remove it completely, your vet may discuss other options such as chemotherapy or radiation. These decisions depend on the tumor type, the stage, and your cat's overall health. There is no single protocol that fits every cat.

For any medication, including antibiotics or pain relief, the dose is calculated by your veterinarian from your cat's weight and health status. Never give your cat a medication made for people or for dogs.

Recovery, Outlook, and Long-Term Management

The outlook for a skin lump in a cat depends almost entirely on the diagnosis.

Benign tumors removed completely usually have an excellent outcome. Basal cell tumors are benign, and surgery is effective [6]. Many cats recover quickly from a small skin surgery and return to normal activity within days.

Malignant histiocytic tumors carry a more guarded outlook. Histiocytic sarcomas begin as localized lesions and can rapidly spread to many organs [1]. That is why early evaluation matters. A lump caught and removed before spread has a better chance of control than one found after the tumor has moved into the spleen or lungs.

Feline pulmonary Langerhans cell histiocytosis is rare and serious. It has usually been diagnosed after death from severe respiratory distress, though diagnosis before death has been reported using lung nodule sampling in two cats, one of which had no breathing signs at all [4]. This is a lung disease, not a skin lump, but it shows that histiocytic disease in cats can be quiet until it is advanced.

Long-term management may include:

Recheck exams every few months to catch new lumps early
Periodic imaging if a malignant tumor was diagnosed
Monitoring appetite, weight, breathing, and energy at home
Keeping a simple log of lump size and location

If your cat has a lump and you want to know what a visit involves and what it may cost, see cat skin bumps and lumps: what the vet will do and how much it costs.

Prevention

There is no proven way to prevent histiocytic tumors in cats. These tumors arise from the immune system, and no vaccine, diet, or supplement has been shown to stop them.

What you can do is catch lumps early. Run your hands over your cat once a week, including the legs, paws, belly, and tail base. Feel for new bumps, scabs, or areas your cat does not want touched. Cats hide discomfort well, so a lump on a toe may show up as limping before you ever see the mass [2].

Keep routine veterinary visits on schedule. Older cats benefit from exams at least once or twice a year, since many skin tumors appear in aged cats [6]. If your cat has a lump that looks like a skin problem but does not respond to standard treatment, ask your vet about other causes. Some conditions that look like skin disease have different origins entirely, which is why can cats get psoriasis is a common question with a more complex answer than most owners expect.

Limitations and When to Contact a Veterinarian

No article can tell you what your cat's lump is. Only a veterinarian who examines your cat and reviews test results can do that. Individual cases need a veterinarian, and the timing below is a general guide, not a rule for your cat.

Contact your veterinarian the same day if:

A lump appeared suddenly and is growing fast
The lump is bleeding, oozing, or has an open sore
Your cat is limping or will not use a leg [2]
Your cat is licking or chewing at the area constantly
Your cat seems painful when the lump is touched

Seek emergency care now if:

Your cat is having trouble breathing or breathing fast at rest [4]
Your cat collapses or cannot stand
There is heavy bleeding that will not stop
Your cat has a swollen, firm belly along with weakness or pale gums

Schedule a routine visit soon if:

You found a small lump that is not changing
A lump has been present for more than two weeks
Your cat has lost weight or has a poor appetite
You notice multiple new lumps

Frequently Asked Questions

Can a cat have a histiocytoma?

A cat can have a histiocytic tumor, but the classic benign cutaneous histiocytoma of dogs is not a recognized feline skin disease. Langerhans cell disorders of that type do not occur in feline skin [1]. Histiocytic tumors in cats are uncommon and tend to be more serious when they do appear.

Are histiocytomas in cats cancerous?

Some are, and some are not. Histiocytic sarcoma is malignant and can spread to organs such as the spleen, lung, and bone marrow [1]. A granular histiocytic tumor on a cat's toe was treated by surgical removal of the mass [2]. Only a pathologist can say which type your cat has.

How do I know if my cat's lump is benign?

You cannot tell by looking or feeling. Benign basal cell tumors in cats can grow quickly and ulcerate, which makes them look alarming even though they are not cancer [6]. A fine needle aspirate or biopsy is the only reliable way to know.

Does a histiocytoma in cats need to be removed?

Not always, but removal is common because it provides a diagnosis and treats the lump at the same time. Surgical removal is the treatment of choice for basal cell tumors and carcinomas in cats [6]. Your veterinarian will recommend removal if the lump is growing, painful, or suspected to be malignant.

What else can cause a lump like this on a cat?

Many things. Infections can mimic tumors, including feline leprosy, which caused a raised, hairless nodule on a cat's lip and was confirmed with cytology, histology, and PCR testing [7]. Cysts, insect bites, and other tumor types are also possibilities. Testing is how you find out.

References

A review of histiocytic diseases of dogs and cats. Veterinary pathology, 2014.
Granular variant of a histiocytic tumor on the toe of a cat: Case report and literature review. Veterinary clinical pathology, 2023.
Epidemiology of Canine Cutaneous Histiocytoma: Insights From Age and Topographic Clustering. Veterinary dermatology, 2026.
Fine-Needle Aspirate Cytology of Feline Pulmonary Langerhans Cell Histiocytosis in Two Cats. Veterinary clinical pathology, 2026.
Splenic malignant fibrous histiocytoma with concurrent hypertension and epistaxis in an Alaskan malamute dog. BMC veterinary research, 2018.
Tumors of the Skin in Cats - Cat Owners. Merck Veterinary Manual.
Autochthonous feline leprosy caused by Mycobacterium sp. strain Tarwin affecting a cat from the Central Coast of New South Wales. Australian veterinary journal, 2016.