• July 26, 2023
  • By Madee Pfeiffer

Malignant lymphoma

Malignant lymphoma is a cancer of blood cells in animals. Malignant lymphoma occurs in a variety of animal species, but this article focuses on the disease in cats. Malignant lymphoma is one of the most common tumors in cats and is sometimes referred to as lymph node cancer. In humans, this form of cancer is called non-Hodgkin lymphoma.

What causes malignant lymphoma in cats
In many cases, a malignant lymphoma in cats develops spontaneously and without an identifiable cause.

Malignant lymphomas can also be caused by various viruses, such as FeLV and FIV in cats. Due to the stray dog policy in the Netherlands, these viruses are almost non-existent. Nevertheless, it is advisable to test cats with malignant lymphoma for these diseases.

The malignant lymphoma leads to an increase in lymphocytes (a type of white blood cell). White blood cells form an important first barrier against all types of diseases. Lymphocytes are formed in lymph nodes distributed throughout the body. The multiplication of the lymphocytes can therefore take place either in the lymph nodes or in other places in the body that are important for lymphocytes. These are; spleen, liver, nose, stomach, intestines and skin.

Due to the nature of malignant lymphoma (white blood cell tumor), this cancer spreads very quickly.

Malignant lymphoma has several “presentations”;

Solitary in which there is 1 single tumor. An example of this is lymphoma in the nose.

Multicentric, with multiple organs affected at the same time. About 15-20% of cats with malignant lymphoma have this manifestation

Malignant lymphoma of the abdomen affecting only organs in the abdominal cavity. These are liver, spleen and kidneys. This form occurs in about 30% of cases of malignant lymphoma.

Thymus form, this form occurs mainly in older cats.

Skin form, the skin is affected. This form occurs in less than 1% of cases.

How do I recognize malignant lymphoma in cats?
Malignant lymphomas therefore have different manifestations. Because of this, it can sometimes be very difficult to identify a malignant lymphoma.

The malignant lymphoma can develop in several organs or in several places at the same time. In addition, it is easy to distribute. In the later stages, it can be very difficult to distinguish malignant lymphoma from leukemia (bone marrow cancer).

How malignant lymphoma manifests itself therefore depends very much on which organs are affected. The lymph nodes can be very large, involving one, several or all lymph nodes. Lymph nodes also enlarge when there is inflammation in other parts of the body. A large lymph node does not always mean your cat has malignant lymphoma.

The spleen may be enlarged. Occasionally this can be felt by your veterinarian, but often this needs to be determined with an ultrasound scan. An X-ray is also an option, but this often provides a much worse picture than an ultrasound examination.

The malignant lymphoma can cause (slight) internal bleeding and blood breakdown, which can lead to your cat developing anemia. You can tell by the fact that your cat is slower and often feels colder in the legs and ears. A malignant lymphoma can also affect the bone marrow.

How is malignant lymphoma diagnosed?
The diagnosis of a malignant lymphoma can only be made with certainty through a microscopic examination. For this, your vet will need to perform a thin needle aspiration biopsy. A small amount of cells is removed through a needle. This biopsy is almost painless and comparable to a blood test. Therefore, anesthesia is rarely required. In some cases, a slightly larger biopsy is required. Sometimes your vet will refer you.

How is malignant lymphoma treated?
Malignant lymphomas can arise from two types of lymphocytes. The T cell or the B cell lymphocytes. Diagnosis and determination of the type of lymphocyte in which the tumor occurs can be helpful in determining the success of treatment and the choice of certain drugs. Chemotherapy is the most effective treatment for malignant lymphoma. The success of this treatment varies greatly depending on the animal and depends on whether the therapy is successful. Most animals appear to be cured and can lead normal lives.

More than 95% of cats have little or no side effects from chemotherapy. Because chemotherapy doses are much lower in animals than in humans, there are far fewer side effects. Chemotherapy can only be carried out in certain clinics, as the substances involved are dangerous. These substances are excreted by your cat via saliva, faeces and urine. The feasibility of chemotherapy therefore depends not only on the type of tumor, but also on your options and your home situation. Research has shown that cats with B-cell malignant lymphoma live longer than cats with T-cell malignant lymphoma. These are natural averages and mean little for the individual animal. The manifestation (which organs are affected) is also very important for the prognosis.

In some cases, the malignant lymphoma is also treated in other ways. An example is prednisone. These are pills. This form of treatment is less dangerous because your cat does not excrete any dangerous substances. However, there are many other side effects associated with treatment with prednisone.

Another option is radiation. This is only possible if the malignant lymphoma is located somewhere in the body (e.g. in the nose). Radiation is often more expensive than chemotherapy.

Surgery is also possible but rarely recommended. There is never really a cure as the tumor comes back in a different place. If the tumor causes problems, an operation is often decided. For example, in the case of an intestinal obstruction. Chemotherapy is often started after surgery to prevent the tumor from coming back.

It is very difficult to say how long a cat will live. In the most common form of malignant lymphoma in cats (abdominal form), half of the cats are still alive after a year. A quarter is still in good health after two years. Chemotherapy often lasts for several months. The effect of the pill treatment often lasts for several weeks.

This text was translated by a translation machine