Mast Cell Tumor (Mastocytoma)
Description of the Disease and Clinical Picture
Mast cell tumors (mastocytomas) are malignant neoplasms originating from mast cells, which are a type of inflammatory cell found in connective and subcutaneous tissue. In dogs, depending on the degree of differentiation of neoplastic cells (Grade I, II, and III), mastocytoma may be localized with less tendency to infiltrate surrounding tissue and low metastatic potential (Grade I) or can be highly invasive and aggressively spread to surrounding tissue with a higher rate of metastasis (Grade III). In cats, the degree of differentiation of the tumor also plays a role in prognosis, but mastocytomas are generally benign in nature. Mastocytoma can interfere with the normal function of the eyelid and irritate the cornea, and the prognosis depends on the degree of differentiation of the neoplastic cells. The tumor appears as a single or multiple formations on the skin or in subcutaneous tissue. It can lie dormant for months, then suddenly start growing intensively. Lesions are variable and can resemble insect bites or many other tumors. They most commonly appear as firm, elevated nodules that are light pink or reddish in color with clearly defined structure and can sometimes ulcerate. These tumors often cause itching and encourage scratching in animals. They are most commonly found in older dogs, although there are cases in dogs younger than one year. There is breed predisposition, and the breeds most commonly affected include Boxers, Pugs, Rhodesian Ridgebacks, Boston Terriers, and Labrador Retrievers. Like in dogs, mastocytomas are most commonly found in older cats, with Siamese cats being predisposed.
 
Therapy
A preliminary diagnosis can be made through a cytological examination of a sample taken from the tumor by fine-needle aspiration (FNA). For a reliable diagnosis, it's best to perform a histopathological examination of the tumor following surgical intervention, based on which the grade of the tumor's differentiation is determined. This examination, along with immunohistochemistry, can determine the degree of malignancy. If the tumor is of a higher degree of malignancy, various tests are necessary for locating metastases (X-rays, ultrasound, CT, MRI). The therapy involves aggressive surgical removal of the skin tumor, along with radiation therapy. If metastases are present, chemotherapy is also advised.
 
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