Histiocytoma in Dogs

A chocolate Labrador Retriever laying outside on a park bench.

The majority of this article is written by a certified veterinarian.

Young dogs are generally healthier than older dogs, but that doesn’t mean you don’t need to be careful about their health. Even young dogs are susceptible to several health issues, including histiocytoma. Many diseases that affect dogs are painful and even downright fatal, but histiocytoma is usually non-fatal

Benign histiocytomas, while not life-threatening, need to be treated as soon as possible.

Histiocytoma is a relatively common occurrence in our canine companions: It happens to about 3 in every 1000 dogs (0.3%).

Here’s everything you must know about histiocytoma in dogs and how to deal with it.

What is a Histiocytoma?

A histiocytoma is a type of skin tumor composed of histiocytes and usually seen in young dogs.

In medical terms, this condition is also known as cutaneous histiocytoma. This skin disease is mostly seen in dogs under the age of four years old.

Histiocytoma in dogs presents as a solitary pink-red lump on the surface of the dog’s skin and is usually hairless in appearance. There are no accompanying lumps in this condition, so you will only find the affected skin tumor.

The lump can appear anywhere on the body but is most commonly found in regions like the head or ears. You will most often find it on ear flaps, and less commonly on the legs, lips, or nose.

Types of Histiocytoma

While cutaneous histiocytoma is the most common one in dogs, there are other, more serious forms of histiocytoma, including the following:

  1. Ulcerated Histiocytoma: Any lump on the skin can ulcerate. An ulcerated tumor on dogs needs to be removed surgically to prevent further infection.
A Black Lab dog against a rosy background.

2. Malignant Histiocytoma: This happens in rare cases where histiocytoma may metastasize to a local lymph node, becoming malignant.

3. Localized histiocytic sarcoma: This, too, is a rare condition that causes the limbs to swell. It mostly affects certain breeds, such as Bernese Mountain Dogs, Golden Retrievers, and Rottweilers.

4. Malignant Fibrous Histiocytoma: This is a type of soft tissue tumor and is not experienced by the vast majority of dogs. It affects all dogs’ organs, causing lethargy, weight loss, and appetite loss. This type is often fatal and isn’t like a normal histiocytoma.

The most important advice when it comes to keeping all types of dogs healthy is to keep visiting your vet for regular checkups.

A Black Lab dog against a rosy background.

Histiocytoma Symptoms

Canine histiocytoma (dog histiocytoma) has a few prominent characteristics for its diagnosis. Histiocytomas are usually small — less than 2.5 mm in diameter — and painless.

The lumps are also

  • smooth,
  • solitary, and
  • without any hair growing out of them.

Any hair loss or scabs around the lump indicates a different infection.

The button-shaped lump should remain more or less the same when observed over a period of a few days.

There shouldn’t be any fluid oozing out of it, and the area around it should not be red, pale, nor irritated.

With that said, you must never try to diagnose and treat a potentially life-threatening tumor by yourself.

It is in the best interest of you and your dog to get a confirmed diagnosis by a vet, as an early diagnosis can save your dog’s life.

What Causes Histiocytoma in Dogs?

• Unconfirmed Cause

Histiocytoma in dogs is caused when a histiocyte shows abnormal rapid growth and produces more histiocytes, forming a lump. There is no confirmed cause of the disease, but there are some theories:

• Immune System Reaction

It is usually thought that histiocytomas can be caused by ticks, viruses, and infections which stimulate the immune system to form a lump on the skin.

• Genetic Predisposition

Though there is no such link found, histiocytoma is more common in certain breeds of dogs and pure breed dogs. This fact links histiocytoma to a genetic predisposition. Boxers and Dachshunds are most prone to getting this skin condition.

A light brown Dachshund puppy lying on a bed and licking themself.

How to Treat Histiocytoma in Dogs?

Histiocytomas in dogs usually don’t need treatment, but if it occurs on a dog’s paw, you might need to get it surgically removed as it can be very irritating to the dog.

In most cases, histiocytoma can resolve on its own. If the tumor is not malignant, all you need is to leave it alone and monitor its progress.

But in some cases, an ulcerated histiocytoma can get infected and requires antibiotic treatment. Some dogs might need histiocytoma removal via surgical means.

The most recommended histiocytoma treatments are:

• Medication

Sometimes, when a lump becomes infected and dangerous, the vet may recommend antibiotics for the dog.

Your vet might also recommend cleaning solutions containing chlorhexidine or iodine to prevent further infection for ulcerated histiocytoma.

• Home Treatment

Before doing any histiocytoma treatment at home, you need to consult your vet to ensure that the tumor isn’t malignant.

When any danger has been ruled out by a vet using histiocytoma dog cytology, you can adopt a simple treatment routine at home:

  • Bathe the dog, cleaning the lump with salt water.
  • Apply apple cider vinegar on the lump with a cotton pad and stick it to the lump with a band-aid.
  • Keep the dog away from licking, scratching, and biting the lump, as such behaviors just increase the chances of the lump getting infected. You can put a cone around your dog’s neck to keep their mouth away.


Can a Histiocytoma Burst?

Usually, no. Histiocytoma shouldn’t burst. These lumps are firm, button-shaped masses of skin that pop up and continue to grow rapidly for about a month.

A chocolate Labrador Retriever laying down in a snowy forest.

And while the lumps should shrink down and resolve on their own, some much more infected lumps might burst.

Can a Histiocytoma Burst?

Usually, no. Histiocytoma shouldn’t burst. These lumps are firm, button-shaped masses of skin that pop up and continue to grow rapidly for about a month.

And while the lumps should shrink down and resolve on their own, some much more infected lumps might burst.

A chocolate Labrador Retriever laying down in a snowy forest.

What if a Histiocytoma Becomes Infected?

An infected histiocytoma is usually treated by washing the infected lump with antibiotics and a cleaning solution from the vet.

If the infection grows and is in a place where it is irritating the dog, surgical removal may be carried out.

Remember not to give your dog any medication without the vet’s consultation.

Can Histiocytomas Be Malignant?

Yes. Although it is very rare in most dogs, histiocytoma can be malignant in nature as well.

A malignant fibrous histiocytoma is a type of cancerous histiocytoma commonly found in soft tissues like tendons and muscles. In rare cases, it can also be present in bones.

In Summary

A single smooth, hairless lump on your dog can indicate histiocytoma. This condition usually resolves itself but does require vet attention to prevent infections and dangerous outcomes.

Carefully follow all of your vet’s advice, as they will help you keep your dog healthy and pain-free for a long time.

A fawn Boxer laying down on a couch.