T and B immunophenotype determination using specific markers (CD3, CD79A, lambda and kappa light chains) in canine biopsies with suspicion of malignant lymphoma

Abstract

Thirty four canine biopsy specimens (lymph node, spleen, intestine and skin) with suspicion of malignant lymphoma were investigated in this study. Histopathological classification and B/T immuno-phenotypes were determined on the routinely processed formalin fixed, paraffin embedded tissue sections using rabbit anti-human CD3, mouse anti-human CD79a and rabbit anti-human kappa- and lambda-light chain as primary antibodies and streptavidin-biotin peroxidase complex procedure for immunolabelling. The T cell lymphomas (CD3 positive cells) constituted 61.5% (16/26) and B cell lymphomas (CD79a positive cells) 38.5% (10/26) of all immunostained specimens, whereas 8 cutaneous tumours with lymphoid-like lesions did not react with any marker of differentiation and could not be diagnosed as lymphosarcomas. Nodal and cutaneous lymphosarcomas were in majority T lymphomas (64.3 % and 62.5 % respectively) which 2 subtypes were identified based on histological criteria: non epitheliotrophic cutaneous T lymphoma in skin and T cell lymphoblastic lymphoma in lymph nodes and in spleen. Among the ten B lymphomas, 9 were positive for lambda and I for kappa light chain and 3 subtypes not associated with any specific tissue localisation were evidenced: B lymphocytic lymphomas (4/10), B lymphoplasmacytic lymphomas (4/10) and diffuse large B cell lymphomas (2/10). When considering the different subtypes, the 26 immunopositive neoplastic tissues consisted in 15.3% lymphocytic, 15.3% lymphoplasmacytic and 7.6% large cell B lymphomas whereas 19.2% and 42.3% comprised non epitheliotrophic and lymphoblastic T subtypes respectively. These results emphasize the interest of B and T immuno-phenotyping for the diagnosis of malignant lymphoma in dog.