ABSTRACT
The aim of this study was to microscopically re-evaluate the melanocytic lesions diagnoses established by the Animal Pathology Laboratory of the Federal University of Uberlândia, in the state of Minas Gerais, Brazil, over a period of eleven years; in addition, to perform a comparative analysis between the conventional histopathological (CH) method and the use of the melanin bleaching (MB) technique with potassium permanganate, sulfuric acid, and oxalic acid solutions. The results of the MB method presented a disagreement in 24.32% of the diagnosis previously by CH, with low agreement (61.0%) and low Kappa coefficient (0.2267). Melanoma was the most frequent lesion, more frequent in elderly and non-breed female dogs. The most frequent melanoma location was in the cutaneous tissue. The presence or absence of a pagetoid spread in cutaneous samples, distribution of melanin, pattern of cell layout, cell morphology, degree of cellular atypia, and the number of mitoses verified after MB were the most important criteria to confirm the diagnosis of malignancy or benignity of the lesions. Evaluating pathologists considered MB to be essential for the majority of diagnoses and an efficient complementary method for the diagnosis of melanocytic lesions, even in cases with a moderate degree of pigmentation.(AU)
Este estudo objetivou reavaliar microscopicamente os diagnósticos de lesões melanocíticas estabelecidos pelo setor de Patologia Animal da Universidade Federal de Uberlândia, em um período de 11 anos, e, com base nesse levantamento, realizar uma análise comparativa entre o método histopatológico convencional (HC) e o método de despigmentação de melanócitos (DM) com permanganato de potássio, ácido sulfúrico e ácido oxálico. A DM revelou discordância em 24,32% dos diagnósticos previamente estabelecidos por HC, apresentando baixa concordância (61,0%) e baixo valor de coeficiente Kappa (0,2267). A alteração mais frequente foi o melanoma, com maior ocorrência em cadelas idosas sem raça definida (SRD). A localização mais frequente dos melanomas foi cutânea. A presença ou ausência de disseminação pagetoide nos casos cutâneos, a forma de distribuição da melanina, o padrão de disposição das células, a morfologia celular, o grau de atipia celular e a quantidade de mitoses verificada após a despigmentação foram critérios de elevada importância para firmar o diagnóstico quanto à malignidade ou benignidade da lesão. A despigmentação foi considerada pelos patologistas avaliadores como essencial para o diagnóstico na maioria dos casos, o que leva a concluir que ela constitui um método complementar eficiente no diagnóstico das lesões melanocíticas, mesmo em casos com grau moderado de pigmentação.(AU)
Subject(s)
Animals , Potassium Permanganate/pharmacology , Pigmentation , Melanocytes/cytology , Melanocytes/pathologyABSTRACT
Canine mammary tumours (CMTs) are the most common type of neoplasm in bitches. As in women, the presence of metastasis in regional lymph nodes is an important prognostic factor in bitches with mammary carcinomas, but the clinical significance of occult isolated tumour cells (ITCs) within lymph nodes is still undefined in this species. The effectiveness of immunohistochemistry (IHC) in identifying occult ITCs and micrometastasis (MIC) was compared with that of the conventional haematoxylin and eosin staining technique. The relationship between tumour size, histological type, histological grade and the presence of metastasis was evaluated. The overall survival (OS) of female dogs with occult mammary carcinomas and ITCs within lymph nodes was analysed. Fragments of mammary carcinoma and regional lymph nodes of 59 female dogs were also evaluated. Histological sections of mammary carcinoma and lymph node samples were studied for tumour diagnosis and lymph node samples were tested by IHC using a pan-cytokeratin antibody. It was found that 35.2% of occult ITCs and 2.8% of hidden MIC were detected when IHC was used. There was a good correlation between the size of the tumour and metastasis to the lymph nodes (P = 0.77). ITCs were observed more frequently in the medullary region (60.7%) and metastases in the cortical region (44.4%). There was no significant difference in the OS between female dogs with occult ITCs and lymph nodes without ITCs. IHC can detect occult tumour cells in lymph nodes that are negative by histopathological examination. Female dogs with nodal ITCs do not have lower survival.
