Caracterização anatomopatológica e imuno-histoquímica do sarcoma histiocítico em cães

Abstract

Histiocytic Sarcoma (HS) is a rare and aggressive neoplasm derived from dendritic cell or macrophage lineages. This study aimed to perform the pathomorphological and immunohistochemical characterization of canine HS cases diagnosed at the Veterinary Pathology Sector of the Federal University of Lavras (SPV-UFLA) between 2014 and 2024. Demographic information, clinical data, and macroscopic and histopathological findings were reviewed. A total of 14 dogs were evaluated, showing an equal distribution between males (50%) and females (50%). Age ranged from 3 to 14 years (mean 8.85 years), with a higher concentration of cases in the 8 to 14-year age group (78.57%). Large-breed dogs were predominantly affected (85.71%). The most frequent racial category was mixed-breed dogs (42.86%), followed by Labrador Retrievers (21.43%). Other affected pure breeds included Bernese Mountain Dog, Boxer, Mastiff, German Shepherd, and Yorkshire Terrier (7.14% each). Regarding anatomical distribution, 100% of the cases were classified as disseminated HS. Macroscopically, the most affected organs were the skin (64.28%) and liver (50%), followed by the lungs, heart, spleen, and skeletal muscle (42.85% each). Lingual involvement occurred in four cases (28.57%), characterized by flat or exophytic and ulcerated nodules. Histologically, the neoplasms were characterized by the proliferation of round to pleomorphic cells with abundant cytoplasm, marked anisokaryosis, and multinucleated giant cells. Immunohistochemistry revealed positive immunostaining for IBA1 in 100% of the cases. Positivity for CD18 occurred in 50% of the cases, and for CD11d in 28.57%, suggestive of the hemophagocytic variant in these animals. There was no immunostaining for CD4 and Ecadherin. It is concluded that HS presented a pathomorphological pattern of high malignancy and an immunophenotypic profile compatible with histiocytic origin in the dogs of this study, predominantly characterized as a disseminated and multicentric disease.