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Mastocytoma in dogs and cats: symptoms and treatment [wet medicine Krystyna Skiersinis

Mastocytoma: mast cell tumors. Symptoms and treatment of mct

Can a small, innocent looking skin lump turn out a dangerous cancer?

Is the doctor really right to recommend that a tiny lesion be removed with a margin several times its size??

Why does the lump behave so strange:

at times it is small and pale, at other times it is pink and much larger?

And what is that name anyway: mast cell tumor?

In this article, you will find the most important information about one of the the most common neoplasms skin in animals.

I explain what symptoms should worry you, when to consult a veterinarian, and what breeds are predisposed to development mastocytomas.

You will also learn what the differences between the different grades of tumors are, as well as how to wisely approach the treatment of mast cell tumors.

  • What are mast cells (mast cells)?
    • Why are mast cells so important?
  • What is mastocytoma?
  • Incidence of MCT and risk factors
    • Mastocytoma in a dog
    • Cat mastocytoma
    • The age of the animal
    • Which dog breeds are most at risk of MCT?
    • Does gender matter?
    • Localization of changes
    • Other risk factors
  • What is mastocytosis?
  • Why do mast cell tumors arise??
  • Symptoms of mastocytoma in dogs and cats
    • Cutaneous mastocytoma
    • Visceral mastocytoma
  • Where tumors are most often formed?
  • How many tumors are usually there?
  • Complications with neoplasm
  • Metastasis of mastocytoma
  • Diagnosis of MCT mastocytoma
    • Biopsy
    • Histopathology
    • Surgical biopsy
  • Determining the stage of cancer
  • Prognosis of mastocytoma
    • The degree of malignancy of the tumor
    • Speed ​​of growth
    • Surgical margins
    • Location of the mastocytoma
    • The number of tumors
    • Stage of the disease
    • Cell proliferation markers
    • C-kit mutation
  • Treatment of mastocytoma
    • Surgical procedure
    • Radiotherapy
    • Chemotherapy
    • Corticosteroids
    • Electrochemotherapy
    • Innovative therapies
    • Relief of the symptoms of paraneoplastic syndrome
  • Follow-up treatment of mastocytoma
  • Cases of pets with mastocytoma
    • Case 1
    • Case 2
    • Case 3

What are mast cells (mast cells)?

Mast cells are cells that are part of the immune system.

Mast cells | Source: Wikipedia

They are present in many tissues, in close proximity to blood vessels.

We find them especially in places that separate the external environment from the inside of the body, such as:

  • skin,
  • respiratory mucosa,
  • mucosa of the digestive system,
  • conjunctiva,
  • nasal cavity.

These are the areas where the "sterile" organism is most exposed to any kind antigens and allergens from outside. They are also present in connective tissue and around nerves.

Mast cells act as watchdogs informing the body about:

  • viral infections,
  • bacterial infections,
  • the presence of toxins,
  • the presence of allergens.

Mast cells are involved in very important immune processes, including:

  • early and late hypersensitivity reactions,
  • blood pressure regulation,
  • reconstruction of connective tissue,
  • wound healing,
  • blood clotting process,
  • angiogenesis (the process of blood vessel formation).

Why are mast cells so important?

In a properly functioning organism, mast cells, when threatened, are supposed to make a lot of "noise " and bring relief to the place of intrusion as soon as possible.

In order to properly fulfill their functions, they are loaded down cytoplasmic granules, containing a large number of bioactive ingredients, including:

  • heparin,
  • histamine,
  • hyaluronic acid,
  • serotonin, and many others.

What happens when an alien appears within the range of mast cells? Degranuluja - that is, they rapidly release the aforementioned pro-inflammatory substances, and the signal for this act is, among others, the binding of the antigen with an Ig class antibody

Noise consists in the fact that, as a result of the released substances, an increased local (sometimes also systemic) hypersensitivity reaction occurs, which is manifested by:

  • widening of the blood vessels,
  • tissue swelling,
  • influx of granulocytes.

We just call it inflammation.

Under normal conditions, this reaction is needed for the rapid mobilization of the body's defenses.

However, sometimes - for reasons not fully understood - it does neoplastic transformation of mast cells.

You already know what mast cells are, but where do these tumors come from? You will find out later in this article.

What is mastocytoma?

Mastocytoma is an uncontrolled, neoplastic growth of mast cells, most often taking the form of a skin or subcutaneous tumor.

What is mastocytoma?

Due to the location of mast cells, proliferation of neoplastic mast cells can start anywhere.

And this is how we distinguish the forms of cancer:

  1. Cutaneous - Mast cell tumor (MCT) - when the cancer process affects the skin and / or subcutaneous tissue.
  2. Visceral - affects internal organs - spleen, liver, gastrointestinal tract, mucous membranes. It occurs much less frequently.
  3. Cases of disseminated mast cell tumor (regardless of where the tumor originates - skin or subcutaneous tissue, internal organs, bone marrow), sometimes in the form of leukemia. And here's a note: in the course of mast cell leukemia mast cells are present in the peripheral blood.
  4. Non-cancerous proliferation, most often within the dermis (mastocytosis).

Some misunderstandings are caused by the naming of proliferative processes concerning mast cells. In veterinary medicine, 2 types of such changes have been described:

  1. Growth reactive - in its course there is a non-neoplastic proliferation of mast cells under the influence of some (known or not) factor. This process is known as mastocytosis (mastocytosis).
  2. Growth cancerous - are typical neoplastic changes, regardless of the clinical course, which are referred to as mastocytomas (mastocytoma).

Difficulties in interpretation result from the fact that often in the literature, the term mastocytoma is defined as multifocal malignant neoplastic processes, which are often accompanied by the appearance of altered mast cells in the peripheral blood (leukemia - mastocytosis leucaemica). To accentuate the neoplastic type of hyperplasia, it is necessary to define it as malignant mastocytosis (mastocytosis malignant).

Yes, this cancer can be very serious

Read on to find out if your pet is at risk and when it can get sick.

Incidence of MCT and risk factors

Mastocytoma in a dog

Mastocytoma in a dog

Cutaneous mastocytoma is the most common skin tumor in dogs.

Of all nodular lesions, approx 25% are mast cell tumors, approx half is mischievous. Mast cell neoplasms account for 16-21% of all skin cancers in dogs.

Cat mastocytoma

In cats, the statistics are slightly lower because 1-9% of all neoplastic lesions found in this species, and 2-7.6% of all skin cancers.

Cat mastocytoma it is usually benign, as local or distant metastases are rather rare.

The presence of recurrence after surgical removal of the tumor is found only in 0-4% cases.

The age of the animal

A dog mastocytoma can occur at any age.

It is diagnosed in animals from 4 months to 18 years of age, but most often it affects older dogs, 8-9 years old.

Cat mastocytoma occurs predominantly in animals 10 years old, however, it was also found in 6-week-old kittens.

Which dog breeds are most at risk of MCT?

Despite the fact that the disease was most often described in hybrids, these tumors are more common in dog breeds such as:

  • boxer, boston terrier, bull terrier (3B-breeds, for some the letter B often means B - Benign - gentle),
  • fox terrier,
  • pug,
  • Labrador,
  • beagle,
  • golden retriever.

Fortunately u boxers and pugs and possibly u golden retrievers Most mastocytomas are well-differentiated, have a mild clinical picture and usually have a favorable prognosis.

Young dogs shar pei are predisposed to occur MCT, and tumors are often poorly differentiated, with a high degree of malignancy, and therefore unfortunately more aggressive.

On the other hand, some studies have reported a reduced risk of developing a tumor in:

  • shih tzu,
  • Maltese,
  • Yorkshire terriers,
  • Chihuahua,
  • dachshunds,
  • miniature poodles.
Cancer in York

In the same study large breed dogs had a higher risk of developing the disease than u dogs of small breeds:

2 times higher in large dogs up to 36 kg, 5 times higher in dogs considered to be giant over 36 kg.

In cats, they are at greater risk Siamese cats, however, the breed predilection is not marked as clearly as in dogs.

Does gender matter?

There was no gender predisposition in dogs.

However, interesting data were provided by statistical analyzes on a group of patients with mastocytoma: it was found that castration or sterilization was associated with increased risk of MCT in both sexes.

In castrated males, this risk is slightly increased compared to non-castrated males, but in the case of sterilized females it was already 4 times greater than in untreated bitches.

Males may have more mastocytomas than females

Localization of changes

It is considered that mast cell tumors in some locations they are characterized by a higher degree of malignancy, more aggressive behavior, and therefore worse prognosis.

Such places include:

  • perianal area,
  • perineum,
  • inguinal,
  • oral mucosa,
  • lips,
  • subcutaneous tissue (in relation to lesions located in the dermis).

Tumors occurring in the subcutaneous tissue are most often lesions of intermediate and high malignancy.

Conjunctival mastocytomas are usually moderately malignant neoplasms (grade II), less frequently grade I, and the least frequently grade lesions (grade III).

However, they pose a challenge for veterinarians due to the difficulty of their complete removal.

Other risk factors

We can certainly include inheritance among other risk factors.

Viral infections were also taken into account in both dogs and cats as a probable etiological factor of mastocytoma, but it could not be proved.

In the samples taken from the cats, the sick were even observed virus-like formations, however, infection has not been transmitted or tumorigenic in laboratory animals.

There was also no association between infection with feline leukemia virus (FeLV), feline immunodeficiency virus (FIV), or feline peritonitis virus (FIP) and the development of these tumors.

In dogs, on the other hand, no virions were found in mast cells, but cancer was induced in very young puppies or in puppies with impaired immune systems.

There is also a greater risk of mastocytoma in the following places:

  • previous injuries,
  • chronic inflammation,
  • burns,
  • the action of irritants.

What is mastocytosis?

In dogs and cats, apart from mast cell neoplasms, they also occur mastocytosis (non-cancerous growths).

Depending on the location and severity of the process, there are 2 forms of mastocytosis:

  • skin,
  • systemic.

In case of cutaneous mastocytosis changes may withdraw spontaneously within a few or several months.

In cats sphinxes and Devonian Recs there have been cases chronic pigmentary urticaria (sphinxes have a family predisposition to its occurrence). The cause of the disease in cats is unknown and is caused by an abnormal mast cell proliferation.

U appears very young kittens itchy, red-brown spots and lumps all over the body.

The second form of mastocytosis - systemic - should be considered in the differential diagnosis when mast cell tumors have developed.

Why do they arise mast cell tumors?

The causes of mast cell tumors are largely unknown.

They have been associated with the already mentioned inflammation of the skin or viral infections.

Currently under consideration c-kit receptor gene mutations. As a result of this mutation, neoplastic transformation of cells takes place, which results in constant stimulation of their proliferation.

Such a mutation was detected in 50% mast cell tumors in dogs have been analyzed, but not reported in cats.

So far, it is not known whether these mutations cause tumors to develop or are just another element of the neoplastic process.

The c-kit mutation is found in approx thirty% dogs with stage III and IV mast cell neoplasm. There is no racial predilection.

I know this is not an easy topic, but by reading on you will learn what the symptoms of mastocytoma are and how you can recognize it in your pet.

Symptoms of mastocytoma in dogs and cats

Cutaneous mastocytoma

Cutaneous mastocytoma in a dog photo of a tumor on a paw | Source: Wikipedia

In dogs, it usually comes to the fore lump, arched above the surface of the skin, shiny.

This is usually the first (sometimes only) reason for consulting a veterinarian.

The appearance and behavior of a skin lesion largely depends on the degree of differentiation:

  • well-differentiated mastocytomas in most cases appear as cutaneous or subcutaneous nodules or tumors with a diameter 1-4 cm. They are well separated from the surrounding tissues, they grow quite slowly.
  • poorly differentiated changes take the form of diffuse skin swellings with poorly marked borders and quite soft consistency. These tumors are characterized by rapid growth, they can reach large sizes, often ulceration appears on their surface.

Huge difficulty in recognizing cutaneous mastocytoma creates the fact that mast cell tumor it can resemble any other (even innocent) tumor on the skin.

Some of them may not change in size for months or even years before they begin to spread rapidly, while others are aggressive from the outset.

There are lesions on the surface of which ulcers appear, there are also those that take the form of small, single or numerous, arched above the surface and red, hairless nodules.

Pet owners often say that they are caressing their pet every day they felt a lump under the skin (of different consistency - according to some it is swollen, others say that it is hard).

The fact is that MCTs are most often formed in the dermis and penetrate the subcutaneous and muscle tissue.

Involvement of the surrounding tissue is most common in rapidly growing tumors.

An important diagnostic symptom is the occurrence of the so-called Darier's symptom.

It consists in the fact that when the tumor is manipulated during palpation or examination, it occurs mast cell degranulation and release of biologically active substances.

The result is redness and swelling of the skin and - sometimes - the appearance of streaky eruptions on it.

During the interview, the owners say that when the dog is petted in this place or even licked by it, the lump very quickly changes its appearance, becomes shiny, and after some time "fortunately " it diminishes.

Cutaneous mastocytoma in a cat appears as round, hard lumps or nodules, from a few millimeters to 2 cm in diameter, most often hairless.

They are formed in the dermis and spread to the subcutaneous tissue, sometimes infiltrating the epidermis.

They are well demarcated from surrounding tissues, usually pouchless.

Visceral mastocytoma

The most common symptoms of visceral form of MCT (this term refers to disseminated or systemic mastocytosis) is:

  • lymphadenopathy,
  • enlarged liver
  • enlargement of the spleen.

In these animals, the following is usually observed:

  • apathy,
  • weight loss,
  • decreased appetite,
  • vomiting,
  • diarrhea.

In patients with visceral disease, malignant mast cells are often found in bloodstream bone marrow, and also in pleural effusion and peritoneal (if any).

Primary has also been reported in dogs, gastrointestinal MCT, which was in the form of tumors spread throughout the gastrointestinal tract.

Here is often observed:

  • vomiting,
  • diarrhea,
  • blood in the stool.

Unfortunately, this form of cancer in a dog is characteristic very bad prognosis.

Where tumors are most often formed?

Tumors in a dog They are most often located in the vicinity of:

  • groin,
  • on the torso,
  • on the limbs,
  • around the genitals and perineum,
  • on the head,
  • on neck.
Dog mastocytoma photo of lesion on the inside of the thigh | Source: Wikipedia

Although this is less common, mastocytomas have also been reported in the area of:

  • claw base,
  • oral and nasal cavity,
  • in the larynx,
  • in the trachea,
  • in the area of ​​the foreskin,
  • in the area of ​​the labia
  • in the perianal area,

Occasionally, tumors also develop in places such as:

  • conjunctiva,
  • salivary glands,
  • digestive tract,
  • ureters,
  • spinal cord.

In cats, they are found mainly on the head and neck (60% cases).

How many tumors are there usually?

Many dogs have these tumors in an isolated form (single tumors), but in 6% cases, tumors may be present in greater numbers.

In cats, mast cell tumors come in 2 forms:

  • as single, rarely multiple skin tumors (which may in some cases metastasize to regional lymph nodes or internal organs),
  • as mastocytomas originating from internal organs (visceral mastocytoma), such as: spleen, liver, lymph nodes, without skin involvement.

Tumors in young cats can be numerous.

They appear simultaneously or one after the other at different intervals.

Complications with neoplasm

Unfortunately, the mere presence of a primary tumor or secondary foci is not the end of our patients' health problems

Other clinical symptoms are also relatively common, which are either the result of bioactive substances released from mast cells. Complications may also be caused by the presence of metastases in internal organs.

These are called paraneoplastic syndromes, and the most common are:

  • Stomach and intestinal ulcers. Most often in the pyloric part of the stomach and proximal sections of the duodenum. Ulcers are most likely caused by the release of histamine by mast cells, which stimulates the parietal cells to secrete larger amounts of hydrochloric acid. Abdominal pain symptoms, decreased or no appetite, vomiting (often with blood), and tarry stools come to the fore. In rare cases, the gastrointestinal wall is perforated as a last resort.
  • Blood coagulation disorders - as a result of tumor manipulation and, as a consequence, degranulation of mast cells and the release of large amounts of heparin by them, local bleeding may occur and problems with its stopping, which is very dangerous, especially during surgery (interestingly, bleeding may occur even if blood coagulation parameters before the procedure were normal).
  • Drop in blood pressure - During surgery, this can lead to a life-threatening situation.
  • Delayed wound healing at the site of tumor removal. Here "merits " should be attributed to the effects of local action proteolytic enzymes and vasoactive amines secreted by the tumor.

Metastasis of mastocytoma

The true metastatic potential of mast cell neoplasms in dogs is not yet fully understood.

However, on the basis of the histological degree, the behavior of the metastases can be predicted:

  • as a rule, a metastatic potential well-differentiated tumors is short (below 10%),
  • in case of moderate grade tumors - short or moderate,
  • undifferentiated tumors they metastasize with frequency from 55% to even 96%.

Metastases - if they occur - mainly appear:

  • in nearby lymph nodes,
  • in the spleen and liver,
  • in other organs of the abdominal cavity.

They appear extremely rarely the lungs.

Cytopathological studies showed that lymph node metastases are observed in 36.2% dogs with mastocytoma.

They most often concern patients with tumors o the highest degree of malice (although they can also accompany low-grade neoplasms).

In the systemic form, neoplastic mast cells can be observed in the bone marrow and in the blood.

Bone marrow involvement is observed in over 50% cases of anaplastic, visceral MCT.

Diagnosis of MCT mastocytoma

Cancer cells - cytology | Source: Wikipedia


The diagnosis of MCT is usually straightforward and performance-based fine needle aspiration biopsy (BAC) or fine needle non-aspiration biopsy (BNAC).

Already when the owner notifies that the nodule has appeared recently, is shiny, changes its size (enlarges once, decreases once), sometimes it is red, the alarm lamp should turn on and in the differential diagnosis we should take into account the mastocytoma.

The mere suspicion of MCT may suggest the appearance of the lesion, the breed predisposition of dogs and the presence of Darier's symptom.

Examination of the material collected by fine needle aspiration biopsy is a quick, sensitive and cheap method. Usually enough for make a diagnosis, but it does not allow for forecasting as to the further course of the disease.

However, a final diagnosis is possible only after carrying out at least cytopathological examination of the biopsy, and the best histopathological examination material collected during a biopsy or surgical removal of the lesion.


Histopathological examination of the material obtained with the help of fragmentary biopsy already allows to determine tumor grade.

Thanks to this, it enables precise planning of the surgical procedure (determination of the width of the surgical margins), prognosis for the future and determination of the appropriate therapeutic procedure.

Surgical biopsy

Surgical biopsy with simultaneous final and complete removal of the lesion.

Its disadvantage is that it requires the maintenance of wide surgical margins while collecting the material (if it is the first diagnostic technique used).

Determining the stage of cancer

All right. We have confirmed a mast cell tumor.

And what's next? What kind of prognosis? What methods of treatment? What is the survival rate of our patient?

To answer these questions, it is extremely important to determine the severity of the disease process.

For this purpose, the World Health Organization (WHO) classification system is used to determine the stage of the disease for dogs with cutaneous MCT:

Clinical stage The type of tumor
ANDSingle tumor confined to the skin with no regional lymph node involvement
AND. (without systemic symptoms)
B. (with systemic symptoms)
IISingle tumor confined to the skin with regional lymph node involvement
AND. (without systemic symptoms)
B. (with systemic symptoms)
IIIMultiple skin tumors or large infiltrating tumors without or with involvement of regional lymph nodes
AND. (without systemic symptoms)
B. (with systemic symptoms)
IVAny tumor with distant metastases or recurrence with metastases (including bone marrow or peripheral blood involvement - leukemia)

Clinical stages of cutaneous mast cell neoplasm in dogs as recommended by WHO.

What the prognosis for our friend will look like, what type of therapy the oncologist will choose, what (more or less) accompanying symptoms we have to take into account, and what the average survival rate of a patient with MCT will be depends on which (inglorious) place in the table will be placed tumor.

However, in order to place it in the right place, a series of tests, often quite invasive, must be carried out.

  1. A thorough clinical examination, complete blood count and biochemical examination, general urine examination - are performed to assess the general condition of the animal, organ capacity, and possible infections.
  2. Blood smear assessment - is to answer the question whether and in what number there are circulating mast cells.
  3. Abdominal X-rays - assessment of internal organs (with particular emphasis on the liver and spleen).
  4. Chest X-rays with lung assessment.
  5. Abdominal ultrasound - again with careful evaluation of the echogenicity of the liver and spleen; assessment of lymph nodes and possible metastatic tumors.
  6. In justified cases, a cytological examination of the bone marrow and regional lymph nodes is performed. A fine-needle aspiration biopsy of nearby lymph nodes should be performed if they are enlarged. However, the suspicion based on the cytological examination should be confirmed histopathologically (in approx 25% in healthy dogs, a small number of mast cells can be found in the preparations of the above-mentioned. lymph). Lymph node metastases observed u 3.2% patients with mastocytoma. They are most common in patients with high-grade tumors (but can also be associated with low-grade tumors). Bone marrow biopsy - Finding more than 10 mast cells in 1,000 nucleated cells indicates the development of the disease. However, one should be very careful with the interpretation of this study.
  7. Cytology or histopathology of the liver / spleen biopsy. Enlargement of these organs by X-ray or ultrasound may indicate generalization of the neoplastic process, but it should always be confirmed by examination.
Golden Retriever X-ray image

Prognosis of mastocytoma

The data obtained from the interview, clinical examination and all other additional tests become, in a way, building blocks, the skillful consolidation of which will allow you to build an accurate and accurate diagnosis.

At the same time, it is a strong prognostic foundation for the further fate of the patient.

However, remember that the entire process of determining a pet's prognosis is complex and depends on many factors.

The degree of malignancy of the tumor

The degree of malignancy is determined during a histopathological examination.

It is considered the most important prognostic factor for dogs with cutaneous MCT.

The schema is the most commonly used scoring system Patnaik for mastocytoma (3-level classification).

There are 3 grades of histological malignancy in it:

  • 1st degree - from well-differentiated cells (mastocytoma G1).
  • 2nd degree - from cells with intermediate differentiation (mastocytoma G2)
  • 3rd degree - from poorly differentiated cells (mastocytoma G3)

1st degree mastocytomas they appear most often in the dermis, less often they reach the subcutaneous tissue.

They are well demarcated from the surrounding tissues.

Cells 2nd degree mastocytoma they often infiltrate the subcutaneous tissue, as well as adjacent tissues.

Third degree mastocytomas - they reach the largest size, infiltrate the subcutaneous tissue and epidermis, their surface is often ulcerated.

Due to the discrepancy between pathologists in the assessment of the degree of malignancy of the mast cell tumor, a new two-stage classification system according to Kupiel. It divides mastocytomas into:

  • low-grade,
  • high-grade histological malignancy.

For example:

stage III mastocytoma it is often associated with the inability to completely remove the tumor by surgery and the appearance of metastases.

In such dogs, the time of remission is much shorter, and the tumor is almost 4 times more likely to cause death than in the case of lower-grade tumors.

The average survival time for dogs with low-grade tumors is above 2 years, while in the case of high-grade tumors - less than 4 months.

Generally speaking, it can be said that:

  • 1st degree MCT are skin-confined lesions, and distant metastases are rare. Death due to recurrence or distant metastases occurs in approx 10% dogs.
  • 2nd degree MCT - usually also changes limited to the skin, but more aggressive. Metastases to nearby lymph nodes and distant sites are found in 45% cases.
  • 3rd degree MCT - death due to recurrence or the presence of secondary foci (also in internal organs) is found in 85% cases.

In cats, the following histopathological types of mast cell tumors are distinguished:

  1. Mastocytic:
    • Well diversified.
    • Poorly differentiated (anaplastic).
  2. Histiocytic.

Most of the mast cells in cats are mast cell mastocytomas, less frequently observed Histiocytic mastocytomas. There is no such clearly marked relationship between the degree of tumor differentiation and its behavior as in dogs.

Poorly differentiated mastocytomas, however, tend to relapse after surgery and metastasize to regional lymph nodes and internal organs.

Speed ​​of growth

Tumors whose growth rate is more than 1 cm in a week their prognosis is worse.

Surgical margins

Surgery: resection of a tumor in a dog

Complete tumor excision during surgery is an important prognostic factor, and it is also an element that determines the need for adjuvant therapy.

Unfortunately, it is often the case that the margins considered by the surgeon do not match those estimated by the pathologist; in short, the tumor was not completely removed.

You should always try to get clean cutting margins, of course - if possible.

Currently, the following guidelines are adopted for the histological evaluation of cutting margins:

  • complete resection - no tumor cells in the distance 1 mm from the edge of the surgical margin,
  • total close resection - mast cells in the area 1 mm from the edge of the surgical margin,
  • incomplete resection - mast cells at the edge of the surgical margin.

Briefly, it can be said that in the case of first and second degree non-metastatic tumors with clean margins, further therapy is often not required, and the patient can only be monitored regularly.

Location of the mastocytoma

There are assumptions that mast cell neoplasms on the limbs they give better prognosis than the occurring ones on the torso.

In turn, tumors in the groin and perineum area usually have a bad prognosis - they give more frequent recurrences.

Localized tumors on the face are characterized by a high, third degree and have a stronger tendency to metastasize to the surrounding lymph nodes.

If there is organ or bone marrow involvement - this usually means poor prognosis.

The number of tumors

Numerous tumors testify to high stage of the disease. Sometimes, however, their occurrence does not have to be worse.

For multiple feline mast cell tumors the prognosis should be cautious or unfavorable due to the risk of metastasis or the formation of further tumors within the skin.

Stage of the disease

The presence of metastases means short survival time.

Enlarged lymph nodes, spleen, liver, or the presence of satellite nodules result in a worse prognosis.

Likewise, coexistence paraneoplastic syndromes it significantly worsens the prognosis for our patient. These are:

  • lack of appetite,
  • vomiting,
  • diarrhea,
  • tarry stools

Cell proliferation markers

In cases where prognosis and treatment are difficult to ascertain, there is an option to determine tumor markers:

  • Silver-consuming nucleoli organization sites (AgNOR) - their average number per cell correlates well with the degree of malignancy of the tumor. A high number of AgNOR in the nucleus of a tumor cell in dogs indicates a more aggressive behavior of the cancer than a low number of AgNOR.
  • Ki-67 - the mean number of Ki-67 positive cells is significantly higher in aggressive high-grade mastocytes. There is also a strong correlation with survival time after surgery.
  • Mitotic index - higher than 10 mitotic figures in 10 fields of view means poor prognosis.

C-kit mutation

It is found in approx thirty% dogs with grade III and IV MCT. Does not show any racial predisposition.

The presence or absence of negative prognostic factors, as well as the clinical picture are key in making decisions about therapy and determining the prognosis.

This should be taken into account when planning time-consuming and expensive therapy.

Read on to learn about the treatment of this cancer.

Treatment of mastocytoma

How to treat mastocytoma? The basic element in the treatment of mast cell tumors is complete surgery tumor resection, sometimes enhanced with additional methods like chemotherapy if irradiation.

The choice of treatment method depends on:

  • the histopathological grade of the tumor,
  • the location of the change,
  • advancement of the disease process,
  • the availability of therapeutic methods,
  • the owner's commitment and financial capacity.

Surgical procedure

A mastocytoma in a dog is a surgical procedure

The first treatment gives the best chance of recovery because the fascia is still intact, there is no scar tissue at the cut site and the tumor is clearly visible.

In dogs, in the case of well-differentiated mast cells (I and II degrees) confined to the skin and subcutaneous tissue (and removable!) the treatment of choice is surgery.

It is assumed that mast cell tumors are removed from 3 cm margin on each side of the lesion and to the depth of one skin muscle (if any), the underlying fascia, and in its absence - the superficial layer of muscles.

Currently, the requirements have been relaxed somewhat, considering that in such cases it is sufficient to keep the lateral margin 2 cm and removal 1 fascia below the tumor.

Why such a stock?

This is to obtain histopathological confirmation that there are no neoplastic cells in the surgical incision line.

In this case, additional treatment is no longer required, and approx 98% of dogs have a good prognosis.

However, if cancer cells are present in the incision line, it is recommended to perform a wider incision (if possible), and the next treatment should include the area of ​​the first excision plus the margin 2-3 cm and further deep tissues.

In the case of moderately or poorly differentiated tumors that are located on the extremities or cannot be completely removed, there are 3 options:

  1. Radical surgery, e.g. amputation of the affected limb.
  2. Radiotherapy
  3. Excision of the lesion in combination with radiotherapy.

If the tumor cannot be removed because of its location or is it G3 mastocytoma it is advisable adjuvant therapy.

Surgical treatment is only palliative and may be combined with radiotherapy and chemotherapy.

A common complication after the procedure is the difficulty in healing wounds, so often the sutures are removed not after 10 days, but even after 3 weeks.


Neoplastic mast cells are quite sensitive to ionizing radiation, even in moderate doses.

This therapy is especially indicated in the case of incompletely removed tumors.

It can also alleviate the symptoms of a systemic disease.

When the tumor is poorly differentiated or metastatic disease is confirmed, the use of radiation therapy as a palliative treatment can improve quality of life by reducing the size of particularly large or irritating tumors, and by stopping bleeding.

However, when dealing with massive tumors, irradiation can cause serious systemic effects. Simply put, radiotherapy can alleviate symptoms, but it does not significantly extend survival time.


It complements surgical treatment and radiotherapy (although it is sometimes used as the only method for various reasons).

Drugs such as vinblastine and lomustine show some efficacy against mast cell tumors in dogs.

Other chemotherapy drugs currently being studied to be effective in dogs include vinorelbine and a new drug paclitaxel (Paclical VET).

Chemotherapy is dedicated mainly to patients:

  • with metastases,
  • with G3 mastocytoma,
  • in the case of incomplete removal of the tumor,
  • if the procedure cannot be performed.

Sometimes it is introduced as the first method before surgery and / or radiotherapy or in the form of monotherapy (some owners do not decide on other forms of treatment).


Mainly used in palliative therapy.

The treatment regimen and the selection of drugs is determined individually by a veterinarian. For example, it might look like this:

  • Prednisolone at a dose of 2 mg / kg / day for 2 weeks,
  • then 1 mg / day for the next 2 weeks,
  • then 1 mg / kg / day every other day.


Electrochemotherapy is the local administration of a chemotherapeutic and exposing the tumor to a current, which enables better penetration of the drug into the neoplastic tissue.

It passes cisplatin in 2 sessions every 7 days.

ECT it is usually well tolerated by patients.

Occasionally, however, there may be local symptoms due to mast cell degranulation.

Systemic symptoms occur rarely and the treatment outcomes are satisfactory in patients with incomplete tumor resection.

Innovative therapies

Application selective inhibitors of the receptor tyrosine kinase, involved in controlling the growth and differentiation of mast cells has been the subject of intensive research in recent years. Only applicable for tumors with a mutation in the proto-oncogene c-Kit (should be confirmed before starting treatment).


  • mastinib (Masivet) - safe and effective in delaying the development of moderate and low grade inoperable or recurrent mast cell tumors (in the absence of regional lymph nodes and distant metastases); in dogs with inoperable moderate to high-grade tumors, the drug significantly prolonged survival,
  • imastinib (Gleevec),
  • toceranib (Pallodia).

Relief of the symptoms of paraneoplastic syndrome

Additional systemic symptoms appear quite often in the course of MCT.

We see them especially in animals with mastocytosis or massive, aggressive mast cell tumors.

In these patients, it is recommended to administer drugs that support and relieve the course of the disease.

Belong to them:

  • H2 receptor antagonists - for the prevention of gastrointestinal ulcers and the treatment of existing ulcers:
    • cimetidine (10 mg / kg twice a day),
    • ranitidine (0.5-2 mg / kg 2 or 3 times a day),
    • famotidine (0.5-1 mg / kg 1 or 2 times a day).
  • Proton pump inhibitors - inhibit the production of gastric juice by the parietal cells of the stomach:
    • omeprazole - (0.5 - 1 mg / kg once a day).
  • In dogs showing signs of ulceration and bleeding from the mucous membranes of the gastrointestinal tract, it has a beneficial effect sucralfate (0.5 - 1 g 3 times a day). It reacts with stomach acid to form a thick, sticky and pasty substance that binds to the surface of the ulcer. In this way, it protects against the digestive effects of digestive enzymes.

In cats, in the case of well-differentiated mast cell tumors, the first and basic treatment is surgery.

Postoperative recurrence or tumor spreading is found in 0-24% cases, more often in the case of poorly differentiated MCTs.

In the case of the histiocytic type, surgery is also recommended in young cats with multiple tumors (histopathologically confirmed).

Many doctors, however, leave such changes "to be observed " because many of them regress spontaneously at different times.

Follow-up treatment of mastocytoma

A very important factor is caring for the patient at home.

It is extremely important both during the entire diagnostic and therapeutic procedure, as well as during convalescence, and then until the end of our four-legged life.

Carefully observe and monitor the condition of the patient's skin, regularly inspect and inspect the tumor site, and perform checkups. Animals that have already developed one mast cell tumor may tend to develop more.

Cases of pets with mastocytoma

Finally, I would like to describe a few cases with G2 mastocytoma, showing how different the clinical course and how different prognosis can give us this insidious and dangerous cancer.

Case 1

West Highland White Terrier, about 9 years old.

A slight change in the skin of the pelvic limb at the height of the ankle joint. The procedure was right - the owner went to the doctor, the tumor was removed.

Unfortunately, due to its location, it could not be removed in clean surgical margins

The doggie comes to us regularly for chemotherapy. He's fine, he can take chemotherapy well. A few days ago I had the pleasure to give him a chemotherapeutic for the last time.

The test results - well - the best since he entered the clinic.

Now it remains to monitor the skin, perform blood tests and

enjoy life. This doggy and his owner were very lucky.

Case 2

An older terrier, often mistaken for a Miniature Schnauzer.

A large fist-sized tumor in the scapular region. The patient came with systemic symptoms:

  • vomiting,
  • lack of appetite,
  • diarrhea.

Sonia endured the chemotherapy patiently, as if knowing that it was helping her

It was wonderful to watch the tumor rapidly shrink in size and the skin above it becoming more and more "saggy".

Unfortunately - during the therapy I was diagnosed with pancreatitis.

This nasty stuff disturbed us unimaginably in our proceedings.

Certain medications could no longer be given, so be careful with chemotherapy.

Together with the owner, we tried to save the pancreas, even with the help of plasma transfusions.

Failed to

When we noticed that the therapy was ineffective and the girl was just getting tired, the owner agreed to euthanasia.

I was very sorry - the cancer reacted beautifully, there was a light in the tunnel.

However, it often happens that it is not the tumor that is the direct cause of the patient's death, but such complications

Case 3

A lovely black Labrador sent for consultation from a distant clinic: a large tumor in the inguinal region.

Previously examined histopathologically - abscess was found.

Despite the implemented antibiotic therapy, "abscess", he did not think to withdraw.

At first glance, the change suggested a mastocytoma:

it was huge, flushed and shining like baubles on a Christmas tree; in addition, streaked skin eruptions along its course.

Surgery was performed and the lesion was sent for histopathological examination.

After a few days, we received information that the pooch was feeling unwell, was vomiting, had bloody diarrhea.

I insisted on mastocytoma, so I recommended to add to the treatment so far:

  • ranigast,
  • claritin,
  • omeprazole.

However, the attending physician did not heed the suggestion

Two days later, an unpleasant message from the owner - the patient is dead.

A few days later, the result from the lab showed up: 2nd degree mastocytoma


I am writing to draw your attention to the importance of choosing a good laboratory to evaluate this type of change.

Samples are often sent to random laboratories with no experience in assessing oncological cases. The consequence of this is choosing an incorrect treatment, which unnecessarily lengthens the time until the introduction of appropriate treatment.

If you want to learn more about the diet for animals with cancer, I encourage you to read the article: "How to feed a dog and a cat with cancer? "

You have noticed lumps in your pet and you are wondering if it is a mastocytoma? You have questions about treating this cancer? Now add a comment under the article, I will try to dispel your doubts.

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