The role of histogenetic signs of tumor cells in the morphological diagnosis of lymphoma in cats

The aim of our study was to identify histogenetic features of tumor cells and assess their role in the pathomorphological diagnosis of lymphoma. The objects of the study were neoplasms from cats of different ages and sexes. The diagnosis was based on macroscopic examination of the removed tissues and histological examination. When examining histological tissue samples, the tumor localization, growth pattern (diffuse, focal, follicular), tumor cell size (small cell, large cell) and histogenetic characteristics (centroblastic, lymphoblastic, immunoblastic) were taken into account. When analyzing the tumor localization, lymph node involvement was revealed in 17.4% of cases, skin and soft tissues - 15.2%, eyes and eyelids - 6.5%, nasal cavity - 15.2%, gastrointestinal tract - 32.6% and other localizations - 13%. Histological examination showed that the large-cell morphological variant of lymphoma is detected in 65.2% of cases, and the small-cell variant in 34.8% of cases. The most characteristic morphological features of large-cell lymphoma are: diffuse tissue infiltration with atypical cells of round and irregular round shape. The cells are large (up to 10 diameters of an erythrocyte). The cell nuclei are large, contain invaginations and irregularities on the surface. The chromatin pattern in the nucleus is lumpy, which allows differentiating multiple nucleoli. The most characteristic morphological features of small-cell lymphoma are: diffuse or focal tissue infiltration with small (up to 5 diameters of an erythrocyte) lymphoid cells. The cell nuclei are round, contain coarse granular, less often, lumpy chromatin. Nucleoli in nuclei are often not differentiated. The presented data can be used to compile histological classifications of tumors in small domestic animals, as well as to develop new targeted treatment regimens for lymphoma.