Pathological and Immunophenotypic Assessment of Canine Splenic Lymphoma in Biopsy and Necropsy Cases

Abstract

Aim: This study aimed to characterize canine splenic lymphoma through a comprehensive evaluation of gross, cytological, histopathological, and immunophenotypic features in both biopsy and necropsy specimens, and to distinguish primary splenic lymphomas from splenic involvement in multicentric disease. Study Design: An observational, descriptive investigation was undertaken on confirmed cases of canine splenic lymphoma submitted for routine diagnostic evaluation. Place and Duration of Study: The study was conducted in the Department of Veterinary Pathology, Madras Veterinary College, Chennai - 07, for one year (June 2011 to June 2012). Methodology: Eight canine cases were diagnosed as splenic lymphoma, comprising six multicentric diffuse large B-cell lymphomas (DLBCL) and two primary splenic B-cell lymphoblastic lymphomas (B-LBL). Specimens were obtained from surgically excised splenic biopsies and post-mortem examinations. Grossly, all spleens exhibited marked splenomegaly, with weights ranging from 120 to 560 g. Patient data revealed a mean age of 8.56 years, with no sex predilection and representation from multiple breeds. Cytological and histopathological classification was performed according to the updated Kiel and World Health Organization (WHO) criteria. Immunohistochemical analysis employed a Pan T-cell marker (CD3) and a B-cell marker (CD79a) to determine lineage. Results: All cases demonstrated a CD3-negative/CD79a-positive immunophenotype, consistent with high-grade B-cell lymphoma. Six cases represented splenic involvement in multicentric lymphoma, whereas two were classified as primary splenic lymphomas. The cytological study of lymphoma revealed homogenous clonal population of lymphoblasts with lymphoglandular bodies with variation in multiple nucleoli and scanty basophilic cytoplasm. Histology showed the white and red pulps were completely substituted by B-LBL neoplastic cells. Cells showed anisokaryosis, prominent nuclei, and chromatin margination. Neoplastic cell showing nuclear indentation with large, single, prominent nucleolus. Histomorphological features corresponded to their cytological classification, and gross lesions were characterized by diffuse enlargement and loss of normal splenic architecture. Conclusion: The integration of gross pathology, cytology, histopathology, and immunohistochemistry enables accurate subtyping of canine splenic lymphoma, with CD3 and CD79a serving as reliable markers for lineage determination. In this series, high-grade B-cell lymphoma was the predominant subtype, underscoring its clinical relevance and the value of immunophenotyping in routine diagnostic practice.