Immunophenotypic and histological characterisation of 109 cases of feline lymphosarcoma

Abstract

Objective To determine and analyse the immunophenotype and histological appearance of naturally occurring cases of lymphosarcoma in Australian cats. Design A prospective multi‐institutional study of naturally occurring feline lymphosarcoma. Methods One hundred and eighteen cats were referred for diagnosis and/or management of suspected lymphosarcoma. Tissue samples for histopathological analysis and immunophenotyping were collected as biopsies or at necropsy from 109 cases. Histological classification of the neoplasms followed the Working Formulation Classification System. Four multi‐species cross‐reactive antibodies were used to classify tumours as having a B or T cell phenotype. Results Seventy‐six (70%) cases were B cell tumours and 28 (26%) were T cell tumours. The remaining 5 (4%) specimens failed to stain with the four antibodies. Histologically, 11 (10%) cases were classified as low‐grade, 72 (66%) were medium‐grade and 26 (24%) were high‐grade tumours. There were no significant associations between age and either histological grade or immunophenotype. Mediastinal and leukaemic cases were significantly more likely to be T cell tumours (P < 0.001 and P < 0.001, respectively). Conclusions In contrast to previously documented studies in the cat, the majority of cases of lymphosarcoma were of B cell phenotype and intermediate histological grade. Based on our data, the histological phenotype of lymphosarcoma is unlikely to predict immunotype, nor are cases of certain immunotypes likely to be of specific histological subtype. Considered in relation to previous reports, the findings suggest that epidemiological factors operating in these cats to produce lymphosarcoma may be different to those operating in North American and UK cat populations.

Cytomorphological and Immunological Classification of Feline Lymphomas: Clinicopathological Features of 76 Cases

“…This was a converse result to a previous study in Australia [9], and it might be due to variation depending on the geographical distribution. Also, a high incidence of alimentary lymphoma and high prevalence of T-cell lymphoma in the alimentary form led to the present result.…”

“…In alimentary lymphoma, while the ratio of T-and B-cell phenotypes varied in previous studies [16,25,27], a high incidence of T-cell subtype was observed in the present study. In mediastinal lymphoma, the B-cell subtype was found up to 1/3 of mediastinal cases in the present study, although there was a report about significant correlation with the T-cell phenotype [9]. Meanwhile, most of the nasal lymphomas were reported to be the B-cell subtype [4,13], and similar prevalence was observed here.…”

“…It was thought to be caused by the limitations of reactivity of immunohistochemistry and PCR analyses, although a few cases might indicate non-B-and non-T-cell lymphomas. Immunohistochemistry using the CD79a antibody has been already reported to be insufficient to determine feline B-cell lymphomas [9,18]. Primers used with PCR for antigen receptor rearrangement have been limited to determine the cellular lineage of feline lymphomas [15,18,26].…”

Immunophenotypic and Histologic Classification of 50 Cases of Feline Gastrointestinal Lymphoma

“…The selection of 2 B-cell markers and 1 T-cell marker for phenotyping in this study was predicated on a 1999 study 11 in which CD79a was not expressed by 7% of the tumors that, based on other criteria, were concluded to be of B-cell type. These investigators also used 2 T-cell markers (CD5 and CD3) but reported that CD3 was sufficient to detect all of the T-cell tumors in their study.…”

Diffuse Multicentric Large B-cell Lymphoma Invading the Central Nervous System in a European Wild Boar (Sus scrofa)

“…; Lozano-Alarcó n et al, 1992), cattle (Bos Taurus; Sasaki et al, 1997), cats (Felis catus; Gabor et al, 1999), and dogs (Canis lupus familiaris; Ponce et al, 2010). The multicentric form is the most common type of animal lymphoma and is seen in two-thirds of swine lymphomas (Jacobs et al, 2002).…”