Carcinoma micropapilar invasivo da glândula mamária canina: análise clínico-patológica, imuno-histoquímica e determinação da sobrevida global

Abstract

Invasive micropapillary carcinoma of the mammary gland, despite its rare occurrence in humans and dogs, is an important neoplasm due to its aggressive behaviour and poor prognosis. The aim of this study was to characterise the clinicopathological and immunophenotypical characteristics and to determine the overall survival of canine invasive micropapillary carcinoma. Of the 22 cases of invasive micropapillary carcinoma selected for analysis, the majority had >3cm neoplasms (15/19; 78.9%) and lymph node metastases (16/16; 100%). Only two cases (2/9; 22.2%) showed distant metastasis. Six cases were classified as stage IV (6/6; 100%). Invasive micropapillary carcinoma were classified as pure (15/22; 68.2%) and mixed (7/22; 31.8%) types. A predominance of vascular invasion (86.4%) and moderate histological grade (16 grade II) was observed. The average overall survival was 120 days and there were no differences between pure and mixed subtypes. Positive immunohistochemical staining for the epithelial marker EMA and negative staining of cystic formations for CD-31, p63 and CKAE1AE3 confirmed the micropapillary nature of the invasive micropapillary carcinomas. Some cases showed positive epithelial staining for p63 (4/20; 20%) and CK34E12 (20/22; 90.9%). Most cases were positive for ER (19/20; 95%) and PR (19/20; 95%) and lacked overexpression of HER-2 (19/22; 86.4%) and EGFR (18/22; 81.8%). The mean proliferation index was 14.8%. These findings demonstrate that similar to human, canine invasive micropapillary carcinoma have aggressive behaviour with high rates of metastasis to regional lymph nodes and short overall survival and may be considered important lesions of the mammary gland in canines.