Clinical and pathomorphological characteristics of cutaneous mastocytoma of dogs

Abstract

According to foreign researchers, mastocytoma is one of dogs' most common (7–12 %). The study aimed to study the features of clinical manifestations of cutaneous mast cells according to the criteria of clinical TNM classification and pathomorphological (cytological and histological) verification of neoplasia according to the two-stage Kiupel classification. We analyzed 24 cases of cutaneous mastocytoma in dogs. During 2016–2020 underwent an entire course of diagnostic and therapeutic measures in the Department of Surgery and Clinic of Small Pets of Stepan Gzhytskyi National University of Veterinary Medicine and Biotechnologies Lviv. According to the criteria of the international clinical TNM classification at the time of admission to the clinic in 7 (29.2 %) dogs established stage I of the tumor, 10 (41.7 %) – II, 6 (25 %) – III, and 14.1 %) animals – stage IV. Based on cytological evaluation of biopsy material selected from tumors and regional lymph nodes, low-grade mastocyte was found in 17 (70.8 %) animals, and in 7 (29.2 %) cases, neoplasia was characterized as high-grade. Histological examination of excisive material selected during surgery in 16 (66.7 %) dogs verified mastitis of low malignancy and, accordingly, in 8 (33.3 %) animals MCTs of high malignancy. The sensitivity of the pathomorphological study was 87.5 % and the specificity of 95.8 %. It has been proven that cutaneous mastocytoma belongs to neoplasms with specific clinical manifestations. Therefore, targeted biopsy should be performed under ultrasound control, fine-needle biopsy (FNA), and material selection for the cytological examination. A comparative analysis of clinical TNM classification data and the results of two-stage histological classification (Kiupel) showed that the size of the tumor and the degree of its malignancy are interrelated, as there is a trend in which, along with increasing T, the clinical TNM classification of cancer, the number of cases of verification of malignant neoplasms is also growing. It was also found that the malignant course of the disease is characteristic of mast cells localized in dogs in areas of the body freely available for permanent injury (limbs, groin, perineum, neck). The obtained data will supplement the evidence of researchers from other countries on the histological structure of tumors and expand knowledge about the pathogenesis of mastocytoma in dogs.