Atypical Presentation of Canine Lymphoma: Non-Traumatic Splenic Rupture in Diffuse Small B-Cell Lymphoma

Small B-cell lymphoma typically has a more favorable prognosis compared to diffuse large B-cell lymphoma (DLBCL).Here, we present the first documented case of canine DSBCL characterized by extensive lymphocyte infiltration in the spleen, leading to splenic rupture and death.A 10-year-old neutered male Shih Tzu presented with lethargy, skin lesions, and generalized lymphadenopathy.On the day of admission, the dog experienced shock, accompanied by bradycardia and hypotension, and subsequently died.Necropsy confirmed splenic rupture, and cytology, histopathology, and immunophenotyping of the lymph nodes confirmed the diagnosis of diffuse small B cell lymphoma (DSBCL).Similar neoplastic cells were identified in the spleen and inguinal skin, establishing a diagnosis of stage V lymphoma with multi-organ infiltration.This case shows that while non-DLBCL B-cell lymphomas are often indolent, certain subtypes, such as DSBCL, may exhibit aggressive behavior, emphasizing the need to carefully evaluate the extent of infiltration in such cases.