Banca de DEFESA: NATHALIA DA SILVA CARVALHO

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : NATHALIA DA SILVA CARVALHO
DATE: 15/07/2021
TIME: 17:00
LOCAL: plataforma virtual Google meet
TITLE:

Clinical-pathological aspects of melanocytic neoplasms diagnosed in dogs at the Department of Pathological Anatomy of UFRRJ (1999-2020) and evaluation of cell proliferation through immunohistochemistry with Ki-67 antibody

KEY WORDS:

oncology, canine, melanoma, immunohistochemistry

PAGES: 87
BIG AREA: Ciências Agrárias
AREA: Medicina Veterinária
SUBÁREA: Patologia Animal
SPECIALTY: Anatomia Patologia Animal
SUMMARY:

Melanocytic neoplasms originate from the proliferation of melanoblasts and melanocytes and are named melanomas when malignant and melanocytomas when benign. Melanomas account for 7% of malignant neoplasms in dogs, which makes it essential to study these tumors. Since they express aggressive behavior and variable histology, complementary tests are necessary for the establishment of diagnosis and prognosis. Mitotic activity may be an important criterion of prognostic value for melanomas, since it estimates the cell proliferation rate. Thus, the objectives of this work were to perform a survey of melanocytic tumors diagnosed in the Sector of Pathological Anatomy (SAP) between January 1999 and August 2020, evaluate the proliferative index of these neoplasms with Ki-67 antibody (MIB-1) and correlate it with prognosis. Histories, necropsy reports, and biopsy reports were evaluated, and slides stained with hematoxylin and eosin (HE) were reevaluated. All data, including epidemiological data, were compiled. Amelanotic melanomas were subjected to immunohistochemical examination with Melan-A antibody in order to secure the diagnosis. Then, immunohistochemistry with Ki-67, used as a cell proliferation marker, was performed and the slides were counterstained with Giemsa. The Ki-67 proliferation index was calculated by counting the cells in 10 random fields of each case under 40x objectives. From the total of 78 cases of melanocytic neoplasms of the SAP, 32 were located in the oral cavity, 29 in the skin, nine in the nail bed and the rest in varied sites, totaling 41 females and 37 males. SRD animals accounted for most of the cases (29). Age was reported in 70 cases, ranging from three to 19 years, with the highest number at 10 years. The most common clinical manifestations reported in the forms were anorexia and dyspnea. In 48 cases it was possible to analyze the histopathological characteristics. Regarding the morphological aspect, the tumors were divided into fusiform (one case), epithelioid (11 cases) or mixed (35 cases). Pleomorphism was marked in 36.9% of the cases and the mean number of mitoses, from all fields, was 10.5. In 36/78 cases (33 melanomas and three melanocytomas) the immunohistochemical technique for Ki-67 was performed. Of these, 12 were positive: three amelanotic melanomas, eight melanotic melanomas and one melanocytoma. When considering the Ki-67 proliferation indices obtained and analyzing the mitoses with the previous diagnosis, the result corroborated the literature, since the malignant variant presented these parameters more evident than the benign variant. It is known that when the index value is ≥ 15%, it is indicative of unfavorable prognosis and is related to mitotic index ≥3 in 10 fields at 40x objective. In 4 cases of melanomas, the proliferation indices corresponded to 15.28%, 15.87%, 19.13%, and 51.3% and the mitotic indices resulted 5, 30, 60, and 70. We conclude that melanocytic neoplasms are equally distributed in both genders and predominantly affect dogs over three years of age, and the most frequent site of lesion is the oral cavity, followed by the skin and nail bed. Regarding melanocytic neoplasms diagnosed in the last 22 years at the Anatomic Pathology Department of the Universidade Federal Rural do Rio de Janeiro, it was observed that the epidemiological aspects related to gender, age, breed and location corroborate those described in the literature, as well as the metastasis sites. The predominant histological type is melanotic melanoma, with a frequency similar to that reported in the world literature. The cell morphology most commonly observed in the present study was the mixed type, unlike most other studies, where the most frequent is epithelioid. Moreover, the proliferative index determined by mitosis count and Ki-67 immunoreactivity varied significantly between melanocytic tumors located in the oral cavity and skin. In the benign variant, the proliferative index was lower when compared to the malignant neoplasms and the counting method used in this study proved to be effective for all types of melanocytic neoplasms studied regardless of their location.

BANKING MEMBERS:
Presidente - 2606155 - VIVIAN DE ASSUNCAO NOGUEIRA CARVALHO
Externa ao Programa - 3377607 - APARECIDA ALVES DO NASCIMENTO
Externa à Instituição - MARIANA CORREIA OLIVEIRA
Externa à Instituição - SAMAY ZILLMANN ROCHA COSTA