Carcinomas sólidos da glândula mamária canina: aspectos morfológicos e imuno-histoquímicos

Abstract

Mammary neoplasms are the most common neoplasms in the dog and represent a heterogeneous group in terms of morphology and biological behavior. Approximately 50% are considered malignant and, given this fact, many attempts have been made to improve the histopathological classification, in order to more accurately assess their biological behavior. The objective of this study was to report the first case of basaloid carcinoma in the canine mammary gland, as morphological and immunohistochemical characteristics of neuroendocrine carcinoma in bitch and propose a subclassification of solid carcinomas and to correlate them with prognostic factors, morphological and immunohistochemical characteristics. 135 cases of solid mammary carcinoma were selected, among 1800 canine mammary neoplasms referred to the Laboratory of Comparative Pathology-ICB / UFMG between the years 2011 to 2018. Histopathological review of the cases was carried out, survival data were obtained and immunohistochemistry technique was performed of cases selected for the markers: chromogranin A, synaptophysin, NSE, PGP 9.5, CD56, pancitokeratin, cytokeratin 14, Ki67 and p63. Solid carcinomas were classified into six subgroups determined by morphological and immunohistochemical characteristics, being those malignant adenomyopithelioma (68/135), carcinoma with solid pattern (22/135), malignant myoepithelioma (16/135), basaloid carcinoma (14/135), neuroendocrine carcinoma (10/135) and solid papillary carcinoma (05/135). Shorter survival time was associated with presence of lymphatic invasion (p = 0.009) in the initial clinical staging (I-III). When considering all clinical stages (IV), vascular invasion (p <0.001) and presence of regional metastasis (p = 0.004) were important prognostic factors. Malignant myoepithelioma had the highest median survival in early and advanced stages. Invasive carcinoma was associated with a greater number of regional metastases. Despite the solid carcinomas of the mammary gland showing the same pattern of cellular arrangement, they demonstrate distinct morphological and immunophenotypic characteristics. Thus, it is essential to distinguish these new histological types, with a better understanding of biological behavior and determination of the prognosis, for the choice of specific and appropriate therapies.