Feline Lymphoma and a High Correlation with Feline Leukaemia Virus Infection in Brazil.

Lymphoma is the most important haemopoietic tumour in cats and has been associated with feline leukaemia virus (FeLV) infection. In Brazil, no studies have established a correlation between FeLV infection and lymphoma. The aim of this study was to characterize lymphomas arising in cats in Brazil anatomically and microscopically, and to correlate these data with FeLV infection as determined by immunohistochemistry for the FeLV gp70 antigen. Fifty-three cats with lymphoma were evaluated. The mean age of junior, prime, mature, senior and geriatric cats was 1.65 years, 4.34 years, 8 years, 12.14 years and 15.5 years, respectively. The anatomical types of lymphoma were multicentric (43.4%, 23/53), mediastinal (33.96%, 18/53), renal (11.32%, 6/53), hepatic (5.66%, 3/53), nodal (3.77%, 2/53) and alimentary (1.89 %, 1/53). The histological types were small noncleaved-cell (33.96%, 18/53), mixed diffuse (22.64%, 12/53), immunoblastic (15.11%, 8/53), lymphoblastic (11, 32%, 6/53), small lymphocytic (9.43%, 5/53), small cleaved-cell (3.77%, 2/53) and large cell lymphomas (3.77%, 2/3). Immunopositivity for FeLV was observed in 56.6% (30/53) of the samples. FeLV positivity was equally distributed between the genders, but predominated in junior and prime cats. The degree of association between lymphoma and FeLV infection in Brazil was higher than that found in other countries, demonstrating the need to prevent and control the factors associated with infection.