NEOPLASTIC DISEASE Feline Lymphoma and a High Correlation with Feline Leukaemia Virus Infection in Brazil T. G. Cristo *,† , G. Biezus *,† , L. F. Noronha *,‡ , L. H. H. S. Pereira *,‡ , J. A. Withoeft *,‡ , L. V. Furlan *,‡ , L. S. Costa *,† , S. D. Traverso * and R. A. Casagrande * * Laboratory of Animal Pathology, Agroveterinary Sciences Center, † Postgraduate Program in Animal Science and ‡ Student of Veterinary Medicine, University of Santa Catarina State, Av. Luı´s de Cam~ oes 2090, Conta Dinheiro, Lages, Santa Catarina, Brazil Summary 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 lym- phoma. The aim of this study was to characterize lymphomas arising in cats in Brazil anatomically and micro- scopically, 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. Ó 2018 Elsevier Ltd. All rights reserved. Keywords: Brazil; cat; feline leukaemia virus; lymphoma Introduction Lymphoma is a tumour of high importance in domes- tic cats, representing 90% of all tumours of hemopoiet- ic origin in this species (Valli et al., 2017). Lymphomas occur spontaneously in many species; however, in cats, these tumours may be associated with feline leukaemia virus (FeLV) infection. FeLV is a potentially onco- genic retrovirus (Weiss et al., 2010). Until the 1980s, the degree of association of FeLV with the development of lymphomas was approxi- mately 70% (Francis et al., 1979). However, this associ- ation has decreased in many countries with the adoption of preventive (i.e. vaccination) and animal population management practices (St€ utzer et al., 2011; Meichner et al., 2012; Beatty, 2014; Collette et al., 2016). FeLV infection was associated with only 15% of feline lymphomas in the USA in 2003 and approximately 13% of lymphomas in Germany in 2012 (Louwerens et al., 2005; Meichner et al., 2012). Mediastinal and multicentric lymphomas are strongly correlated with FeLV infection (Hardy et al., 1980; Vail et al., 1998; Weiss et al., 2010; Meichner et al., 2012). Alimentary lymphomas are common in J. Comp. Path. 2019, Vol. 166, 20e28 Available online at www.sciencedirect.com ScienceDirect www.elsevier.com/locate/jcpa Correspondence to: R.A. Casagrande (e-mail: casagrande_vet@yahoo. com.br). 0021-9975/$ - see front matter Ó 2018 Elsevier Ltd. All rights reserved. https://doi.org/10.1016/j.jcpa.2018.10.171