Buck is 16-years-old bologna dog that came in veterinary clinic “Sofia” complaint that over the right upper lip appeared nodule that grows quickly and is not affected by systemic antibiotics and topical medications. According to owners the dog is in good condition for his age. The examination reviewed button – like, ulcerating lesion on the right upper lip. There were no reactive regional superficial lymph nodes. An auscultation reviewed a slight cardiac murmur. Everything else from the examination was normal.

We did FNA ( fine needle aspiration biopsy ) of the lesion and regional lymph node. The samples were stained with Hemakolor.

The diagnosis is highly differentiated (I degree) mastocytoma.

Mast cell tumor is composed of mast cells – these are cells derived from bone marrow and mature in the connective tissue. Mast cells are specialized cells that when stimulated , separate biologically active substances: histamine, heparin, serotonin, prostaglandins and proteolytic enzymes. They are extremely important in the immune response, but can be dangerous when they are in excess.

Mastocytoma represents tumor proliferation of mast cells. They are usually dermal and subcutaneous malignancies, which constitute the vast majority of malignant skin tumors in dogs (around 11-27 %). Usually affects older dogs, but also emerging in younger. Mastocytoma are localized mostly on hind legs , head, neck, foreskin and perineal area. Breeds in which the most common are: Boxer, Boston Terrier, Weimaraner, Shar – Pei, Pug, English and French Bulldog, Labrador and Golden Retriever and others.

In Bucky’s case surgery was not an option, so medication therapy was started and after about three weeks, the result was here!

In cats mastocytoma is the fourth most common skin cancer. It takes 2 to 15 % of skin malignancies. More susceptible are the cats above the middle age (8-10 years). As a breed , literature data indicates that the Siamese are the most commonly affected, but lesions are seen in other breeds.

CLINICAL FINDING: there is a small , hard, button – like lesion. Lesion could be like erythema, ulcerating and/ or with loss of fur ( alopecia ) , also it could look like normal skin. Rarely mastocytoma can manifest as soft, unformed, fluctuating masses that might be confused with an abscess or lipoma. Sometimes the lesion can be very large, diffuse , even can take up to 60% of the body surface. Regional lymph nodes are involved in the process and react with 70% of cases

The clinical manifestations of the disease vary and usually reflect the degree of involvement of different systems in the process , and the presence , respectively absence of paraneoplastic disorders. Signs that can be observed are: local pruritus, anorexia, dizziness, vomiting, diarrhea, melena, abdominal pain, microcytic hypochromic anemia and others. As a rule, systemic mastocytosis  occurs with systemic disease presentation, and the skin form – not. The release of biologically active substances from the granules of mast cells leads to gastric ulcers , cardiopulmonary disorders, peritumoral reactions, delayed healing of wounds, influencing coagulation factors and other. Most paraneoplastic disorders associated with mastocytoma are due to the release of histamine by mast granules. This process is not linked to the clinical stage, histological grade of tumor, etc. – in all patients with mastocytoma elevated levels of histamine in the blood is observed.

Histamine acts mainly on two types of receptors – H1 and H2, which are found in different systems in the body – gastrointestinal, vascular walls, cardiac muscle, respiratory system and others. Histamine may also act locally. Usually it is unlocked in stimulating the disintegration of granules in mast cells in a variety of external influences – rough handling in the area of the lesion, even higher or lower ambient temperatures can cause damage to the granules and thus the release of biologically active substances. This in turn causes a reaction – peritumoral edema, erythema, pruritus and others.

This is Angel, a 13 year old cat. It  was brought to our clinic with complaint of recurrent vomiting, which in the past two weeks has worsened. Owners noticed a flat body the size of a coin in the chest area, in the course of one month it has increased double the size.

A thorough examination showed that regional lymph nodes were also reactive.

Mastocytoma in cats has 3 main clinical presentations:

• Skin
• Lymphoreticular/ visceral (affects are liver, spleen , regional lymph nodes , etc.).
• Gastrointestinal

DIAGNOSIS: The diagnosis “mastocytoma” is relatively easy. Different methods are used for this purpose.

• FNA – fine needle aspiration biopsy: is a cytological evaluation method of the cell composition of the lesion. Prepare colored preparations of the samples taken from the tumor that are examined under a microscope . In many cases, this method is absolutely sufficient for proper diagnosis . It is necessary to make a differential diagnosis with other round cell neoplasia.
• Histological examination: is examination the piece of the neoplasia, after preparing a histological microscope slide. This method is used to confirm the diagnosis, when cytological examination is not enough and to categorize specific tumor.

Mast tumors are divided into 3 histologic categories:
I. Well differentiated – mature cells
II. average differentiated
III. Poorly differentiated – anaplastic mast

Poorly differentiated mastocytomas are the most dangerous and the worst prognosis.When well differentiated appearance is a relatively optimistic prognosis.

In the case of Angel it is average differentiated mastocytoma which unfortunately is doubtful prognosis.

In cats, there’s also a little different histological classification – distinguishing two histological subtypes skin mastocytoma:
I. Histiocytic type (often found in young Siamese under 4 years of age)
II. Mast type (more common in animals over 4 years without breed predisposition, often mixed breed)

Of course, in the diagnosis of this disease many other methods are used such as ultrasound, X-ray, blood tests, etc that help to clarify the picture. The listed methods are particularly useful in systemic mastocytosis when lesions can be found in various internal organs.

THERAPY AND PROGNOSIS:  in dogs and cats approach to already diagnosed mastocytoma is similar. Different methods are used for the therapy with varying success.

• Surgical removal of neoplasia
• Chemotherapy (prednisone is commonly used)
• Radiotherapy
• Use of H1 and H2 receptor blockers (cimetidine, sucralfate, etc)

Naturally, the symptomatic therapy is important too, especially for systemic course of the disease.

There are some methods in the testing process, such as the use of deionized water in vivo to stimulate rupture of the mast cells and destruction of the tumor, since mast cells are sensitive to hypoosmolarity.

The prognosis varies and is most often determined by the histological grade of the tumor. Poorly differentiated  tumors usually have a poor prognosis, when well differentiated are optimistic in early identification and proper conduct of therapy.

Angel was also taken on medication and we soon expect her for check up.