Linfoma em cães: aspectos anatomopatológicos, caracterização do envolvimento do sistema nervoso central e linfoma hepatocitotrópico.

Abstract

A retrospective study of the necropsy cases of dogs diagnosed with lymphomas was carried out in the Laboratory of Animal Pathology of the Veterinary Hospital Prof. Dr. Ivon Macêdo Tabosa of the Federal University of Campina Grande, Patos Campus, Paraíba over the period from January 1986 to December 2018. The study resulted in three chapters of the dissertation. The first one entitled "Clinical and anatomopathological characterization of lymphomas in dogs: 51 cases" adressed the frequency of dogs with lymphomas, their age, sex and breed profiles, clinical signs, macroscopic and microscopic findings. Of 2600 necropsies performed in dogs, 304 were diagnosed with neoplastic disorders and of these, 51 with lymphoma. Males were more affected than females and average age of dogs was 7.8 years old. The mixed breed, Rottweilers and Poodles were the most affect breeds. The main clinical signs were: anorexia, lymphadenomegaly, pale mucosae, jaundice, apathy, prostration, skin lesions and vomiting. Five animals had isolated lymphomas in the liver (2 cases), heart (2 cases) and kidney (1 case). Already 46 had multicentric lymphomas affecting, mainly liver, lymph node, spleen, kidneys, lung, skin and heart. Different macroscopic and microscopic lesions were visualized. The second chapter entitled "Clinical, anatomopathological and immunohistochemical features of lymphomas envolving the central nervous system in dogs: 7 cases" aimed to describe seven sporadic cases of secondary lymphomas of the central nervous system in dogs pointing the characteristics of the study population, the clinical signs, the macroscopic, histopathological and immunohistochemical findings. Four animals were males and three females and the mean age of the affected dogs was 7.4 years old. Three animals were mixed breed, two Rottweilers, one Dachshund and one German Shepherd. Clinical signs consisted of seizures, ataxia, local pain, opisthoton, bilateral blindness, and Schiff-Scherrington syndrome. Mainly, macroscopic lesions occurred in the meninges and in the encephalon. Microscopically the main distribution pattern was intravascular and four cases were classified as nonspecific peripheral T-cell lymphomas and three as intravascular T-cell lymphomas. The third chapter titled "Hepatocytotropic T-cell lymphoma in a dog: case report" included a rare case of hepatocytotrophic lymphoma in a cross-breed dog, 11-year-old male, highlighting its clinical, anatomopathological and immunohistochemical findings. The dog showed inappetence, anorexia, vomiting, diarrhea, jaundice, hepatomegaly and alterations in hepatic and renal serum biochemistry. At the necropsy we observed a diffusely yellowish and enlarged liver with bulging edges and accentuation of the lobular pattern. Microscopically, diffuse infiltration of neoplastic lymphoid cells was observed in the sinusoid lumen and dissecting the hepatocyte strands individually or in small clusters. Similar infiltrate was observed in the kidneys. The immunohistochemical profile revealed CD3 / CD20 co-expression with a predominance of CD3-positive neoplastic cells being classified as hepatocytotropic T-cell lymphoma. With this work it was possible to determine the frequency of dogs with lymphomas diagnosed at necropsies at the Laboratory of Animal Pathology of the University Federal de Campina Grande found that it is a frequent neoplasm in the routine and one of the main causes of death in these animals. They affected the various systems including the nervous system and showed a great variety of clinical signs and macroscopic and microscopic lesions.