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