Work

Spontaneous primary B cell lymphoblastic lymphoma of the spleen of a 24-month-old male C57BL/6 mouse.

Year: 2026

Type: article

Abstract: Spontaneous lymphoid neoplasms are common among aged C57BL/6 mice, predominantly manifesting as T cell lymphomas. However, primary B cell lymphoblastic lymphomas are rare and poorly characterized, especially in laboratory animals. This case report describes a primary B cell lymphoblastic lymphoma in the spleen of a 24-month-old male C57BL/6 mouse. Gross examination revealed an enlarged spleen with a homogenous, white, firm mass replacing the normal parenchyma. Histopathological analysis revealed that the splenic architecture was diffusely replaced by neoplastic lymphoid cells with high mitotic activity. Immunohistochemical staining confirmed the B cell origin of the neoplasm, demonstrating strong CD20 positivity and CD3 negativity. This case underscores the importance of detailed pathological evaluation in aged laboratory mice, especially to distinguish spontaneous lesions from treatment-induced effects in experimental studies. These findings contribute to the understanding of lymphoid neoplasms in laboratory animals, as well as provide valuable reference data for pre-clinical research in toxicology and oncology.

Source: PubMed Central

DOI: 10.30466/vrf.2025.2065919.4839