Alimentary lymphoma in a Quarter Horse

Clinical case report

Abstract

Lymphoma is a lymphoid hematopoietic tumor and one of the most common malignant neoplasms in equines. This report describes a case of lymphoma in a Quarter Horse, diagnosed post-mortem through histopathological analysis of necropsy findings. The consultation was prompted by chronic weight loss and 24-hour evolution of diarrhea. Clinical examination revealed a body condition score of 3/9, depression, congested mucous membranes, fever, tachycardia, tachypnea, and normal intestinal motility. Hematological and biochemical analyses showed leukocytosis, lymphocytosis, neutrophilia with a left shift, and hypoalbuminemia as the most relevant abnormalities. Euthanasia was performed due to lack of response to treatment, and necropsy was conducted 2 hours post-mortem. Lymphadenopathy and nodules were found on the surface of the spleen, as well as lymphadenopathy in the cecum and large colon. Histopathological examination revealed an abundance of tumor-like lymphocytes, with evident pleomorphism, anisocytosis, anisokaryosis, and multiple mitotic figures in the spleen, cecum, colon, and regional and satellite lymph nodes. The villi and lamina propria of the cecum and colon were infiltrated with tumor cells. This is the first report in Uruguay of a clinical-pathological case of alimentary lymphoma (Type 5b, WHO) with manifestations in blood, several organs, and systemic signs. Cellular immunophenotyping could have provided a more precise diagnosis of the disease.