Oral T-cell-rich large B-cell lymphoma in a horse.

This research explores a case of an uncommon large B-cell lymphoma, rich in T-cells, in a horse’s mouth, which resulted in aggressive growth and local invasion.

Case Presentation and Symptoms

• The research details the case of a 25-year-old Crioula mare exhibiting significant signs of health issues due to a tumor. The mare had an increased volume on the right side of its face, trouble breathing (dyspnea), lack of appetite (anorexia), and was losing weight progressively.
• The investigation revealed that the tumor was located in both the rostral and caudal sinuses of the horse, indicating the significant extent of the disease. This oral tumor was noted to be highly invasive, impacting surrounding structures significantly.

Postmortem Discovery and Diagnosis

• An autopsy was performed on the mare, revealing a yellowish tumor that had a varied consistency, ranging from soft to firm. This mass had infiltrated multiple bones of the mare’s skull and had extensively invaded the hard palate and masseter muscle (a major muscle involved in chewing).
• Upon microscopic examination, the researchers found that the tumor was an undifferentiated malignant neoplasm, meaning it was a cancerous mass of cells that had lost their specific characteristics. The tumor comprised of a densely populated mass, with largely neoplastic (abnormal growth) B-lymphocytes, identified by the CD20 marker. The B-cells were mixed with numerous small, reactive T-lymphocytes, identified by the CD3 marker.
• The specific composition of the tumor led to the diagnosis of an uncommon type of lymphoma – oral T-cell-rich large B-cell lymphoma. The abundant presence of B and T cells denotes their crucial role in the tumor development and could account for the aggressive progression of the disease.

Significance of the Study

• Given the rarity of such tumors, this study adds to the limited body of knowledge surrounding T-cell-rich large B-cell lymphoma in horses. It helps improve the understanding of the disease manifestation, progression, and the potential impact on the animal’s health.
• The findings could guide diagnoses in similar cases and potentially contribute to improving therapeutic approaches to manage such aggressive lymphomas in horses.