Feline nasal and nasopharyngeal lymphoma : cytological, histological and immunohistochemical evaluation

Feline nasal lymphoma: cytological, histological and immunohistochemical evaluation. Santagostino SF*1 DVM, Mortellaro CM2 DVM, Caniatti M1 DVM, PhD, ECVP, Roccabianca P1 DVM, PhD, ECVP Facoltà di Medicina Veterinaria, Università degli Studi di Milano, Italy 1 Dipartimento di Patologia Animale Igiene e Sanità Pubblica Veterinaria, Facoltà di Medicina Veterinaria, Università degli Studi di Milano, Italy 2 Dipartimento di Scienze Cliniche Veterinarie, Facoltà di Medicina Veterinaria, Università degli Studi di Milano, Italy Abstract. Lymphoma is the most common primary tumour of nasal cavities in cats. The purpose of this study is to describe clinical and cyto-histological findings in 24 cats with nasal and nasoparhyngeal lymphoma. Clinical evaluation, radiographs, CT scans were performed. Pinch biopsies were collected from all cases, formalin fixed and routinely processed for histology and immunohistochemistry. In selected cases imprint cytological specimens were stained with May Grünwald Giemsa and evaluated in parallel with histology. Immunohistochemistry for CD20, CD3, FeLV and Feline Calicivirus were performed. The WHO classification of lymphomas was applied. Of the tumors, 16/24 were classified as primary nasal lymphoma, 5/24 involved both nasal and pharinx, 1/24 involved pharyngeal tissue; 1/24 originated from the fronto-nasal region. Most cats were DSH (17/24), with a mean age of 10,4 years (range 3-15 years) and a male prevalence (F/M=0,84). The most common clinical sign was sneezing, followed by dyspnea, nasal and ocular discharge, stertor. Radiographical and endoscopical examination were performed with tumor masses detected in 16/21 cases. Two cats received multi-agent chemiotherapy, but were euthanized; one cat received radiotherapy and is still alive with a survival of ten months. Endoscopic pinch biopsies were collected in all cases. In 17 cases cytological specimens were also available. Histologically, 20/24 samples had a diffuse growth pattern and only 4/24 had a follicular or nodular growth. Twelve lymphomas were classified as small cell, 3/24 as medium cell and 9/24 large cell (6/9 with immunoblastic morphology). Epitheliotropism was detected in six cases (5 immunoblastic and 1 small cell lymphoma). Immonophenotypic analysis indicated a B cell origin in 19/24, a T cell origin in 3/24 and 2/24 cases were diagnosed as non B-non T cell lymphomas. Six cases were FeLV gp70 positive, 9 were FeLV p27 positive; 16 were positive for Calicivirus αFCVS19, but none was positive for FCV43 antigen. Five cases were lost to follow up, in 4 cats full necropsies were performed and in one case the tumour was limited to the nasopharyngeal tissues while in 3 multiorgan involvement was observed. Nasal and nasopharyngeal lymphomas were more commonly of large cell type and B cell origin and frequently expressed FeLV proteins. The role of Feline Calicivirus could not be clearly interpreted and needs further clarification. Novel tumoral entity identified in this site was follicle centre cell lymphoma grade I. Most cases demonstrated aggressive behaviour and a poor prognosis with tendency to spread to internal organs.