Introduction

Feline lymphoma is regularly found with poor prognosis for survival time and disease-free survival time. In cats, both B-cell and T-cell derivations are developed to lymphoma but differ in malignancy and prognosis. Pax-5 is a nuclear transcription factor which plays a major role in B-cell differentiation and proliferation. Currently, Pax-5 is used for diagnosis the lymphoid neoplasm of B-cell origin in human and canine B-cell lymphomas; however, no data is available in feline.

Objectives

To develop immunohistochemistry protocol and to elucidate the Pax-5 immunophenotype in feline B-cell lymphoma.

Methods

Seven biopsy samples from cats' lymph nodes and extranodal mass, were diagnosed as feline lymphoma by routine histopathology. Immunohistochemistry (IHC) was performed to detect an expression of Pax-5 and CD3; indicating the B-cell and T-cell lineage, respectively. Histological classification was done according to updated Kiel's classification.

Results

Immunohistochemistry of Pax-5 revealed intense nuclear immunostaining of B-cell lineage whilst that of CD3 showed intense cytoplasmic immunostaining of T-cell lineage. Seven feline lymphomas were classified as low grade B-cell lymphoma (5/7) and high grade B-cell lymphoma (2/7). Low grade B-cell lymphomas are accounted for three cases of lymphocytic subtype and two cases of centrocytic subtype. High grade B-cell are categorized as one case of centroblastic subtype and one case of immunoblastic subtype.

Conclusion

Pax-5 immunostaining showed more specific immunophenotype of B-cell. These results are accordance to human and canine B-cell lymphomas from previous reports. Therefore, P-5 immunophenotyping might be a potential marker to use as a new diagnostic tool for feline lymphomas.