Use of minimally invasive techniques in the diagnosis and characterization of lymphoid hematopoietic tumors in dogs

Tese especialmente elaborada para obtenção do grau de Doutor em Ciências Veterinárias na especialidade de Ciências Biológicas e Biomédicas, área científica de Clínica ; ABSTRACT - Lymphoma is the most common hematopoietic tumor in dogs, presenting a variety of clinical and morphological forms originating from lymphoid cells. In contrast, multiple myeloma is considered rare. The introduction of minimally invasive techniques in human medicine has had a significant impact, allowing for the accurate diagnosis, screening, and monitoring of neoplasms in humans. The potential for applying these techniques to domestic animals, such as dogs with hematopoietic neoplasias, still lacks the necessary additional studies to assess their efficacy and applicability in veterinary medicine. The main objective of this work was the implementation and use of minimally invasive diagnostic techniques, such as cytology, cell block, immunocytochemistry and PCR for antigen receptor rearrangements (PARR), in the diagnosis of dogs with suspected lymphoid hematopoietic tumors. Initially, the research focused on evaluating and comparing various minimally invasive techniques used in cytological aspirates to diagnose multicentric lymphomas in 38 dogs. It was shown that these approaches make it possible to partially diagnose and characterise multicentric lymphoma in dogs, suggesting the feasibility of obtaining the necessary diagnostic material in a single consultation, which leads to significant gains in terms of cost and time savings without compromising diagnostic accuracy. This work then reinforces the importance of using cell blocks in the diagnosis of lymphoid cell neoplasms by demonstrating their potential in aiding the diagnosis of canine multiple myeloma (MM). Faced with the hypothesis of lymphoid neoplasms with a plasma cell phenotype in dogs, cell blocks from aspiration punctures of the spleen and bone marrow were taken for immunohistochemical analysis. The results of the immunophenotyping allowed the diagnosis of MM and excluded ...