1Center of Excellence in Ruminant Abortion and Neonatal Mortality, Department of Pathobiology, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran
2Departmednt of Clinical Sciences, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran
Postmortem examination of a 5.5-year-old Holstein cow with history of sudden death showed a very huge spleen (120 × 45 × 10 cm) associated with severe haemoperitoneum. Histopathological findings included extensive infiltration of medium to large sized lymphocytic and lymphoblastic cells with small amounts of cytoplasm, round nuclei with coarsely granular chromatin in the spleen, and limited foci of similar cellular infiltration in the liver. This case was diagnosed as a fatal splenic rupture caused by an atypical malignant lymphoma.