Análise clínica e sobrevida de cães com mastocitomas cutâneos metastáticos e sua relação com características histológicas, imunohistoquímicas e genéticas.

Abstract

Mast cell tumors are one of the most important cutaneous malignancies in dogs, and can present with variated biological behaviour and prognostic. Gathering and evaluating tumor and patient prognostic characteristics can be of great value in the decision making process for the clinical oncologist. The goal of this research was to compare the presentation of the main histological, imunohistochemical and genetical characteristics evaluated commonly in mast cell tumors, in both the cutaneous mass and its lymphonodal methastasis. To achieve that, patients referred to the Oncology sector of Federal University ou Minas Gerais (Brazil) that presented with histologically diagnosed mast cell tumor with also histologically detected lymphonodal methastasis were evaluated. The evaluated characteristics included histological graduation bt the Kiupel and Patnaik systems, mitotic index, growth fraction estimated by the percentage of Ki-67, KIT receptor pattern and mutational status in exon 11 of the c-KIT oncogene. No correlation was found between the cutaneous mass and its lymphonodal methastasis regarding the evaluated features, thus showing the need to perform these analysis in both locations, when affected, to better determine the prognostic and course of treatment for the patient. It was also noted a greater incidence of internal tandem duplications in exon 11 of the c-KIT oncogene, which happened in 35% of cases, suggesting that patients of advanced clinical staging and worse prognosis have these mutations more frequently. The study also demonstrated a need to evaluate a panel of prognostic characteristics, and not any of the aspect individually, under risk of underestimating or overestimating the aggressiveness of a mast cell tumor. The conclusion was that, in cases of metastatic mast cell tumors, it is important to evaluate a comprehensive panel of prognostic characteristics in the primary tumor but also in the metastatic lymphnode.