Avaliação da citologia aspirativa com agulha fina e graduação citológica de Robinson para diagnóstico de tumores mamários caninos

Abstract

The cytological examination offers advantages for being simple, cost-effective, relatively non-invasive, rapid and is used for the preoperative diagnosis of canine mammary tumors (CMT), although histopathological examination is considered the gold standard in CMT diagnosis. In human breast cancer (HBC), the Robinson cytological grading system is used. However, in Veterinary Medicine, the prognostic value of cytological grading is not yet established. Therefore, the objectives of this study are: to evaluate the accuracy of cytological diagnosis and the Robinson cytological grading system in comparison with the histopathological examination of CMT; to compare the cytological and histological grading systems with tumor behavior; to determine an association between the Robinson cytological grading system, the occurrence of metastases, and patient survival. Medical records of female dogs with mammary tumors treated at the Veterinary Hospital of the Federal University of Uberlândia from January 2020 to December 2022 were selected. A total of 96 samples were selected, including multiple samples from the same female dog. Subsequently, cytological and histological slides used for diagnosing mammary tumors in these dogs were selected and evaluated to compare the cytological grade with the histopathological grade (gold standard). The age of the evaluated dogs ranged from 3 to 16, with 84% being elderly and 65.33% being intact. 50.67% of the dogs were mixed-breed, and the most affected breed was Poodle (16.00%). The most frequent histological type in the histopathological evaluation was carcinoma in a mixed tumor (36.46%), followed by tubulopapillary carcinoma (20.83%). Most of the dogs presented with grade 1 tumors (53.12%). There was a 56.25% agreement between histological and cytological diagnoses regarding the cytological test's ability to determine the histological type of CMT. The cytological examination strongly indicated mixed tumors but not simple tumors. There is an association between cytological grade and histological grade, and the agreement was considered substantial. Survival was not related to cytological grade, but dogs with grades 2 and 3 had a shorter average survival. Additionally, there was no difference in the distribution of tumor grades concerning the occurrence of lymph node and distant metastases. The progress of cytopathology is evident, but there is a need to implement new collection techniques due to the heterogeneity of CMT. The cytological grading criteria established by Robinson are useful, and the technique is promising; however, it is essential for the veterinary pathologist to be adequately trained for cytological grading to have clinical relevance.