Sinonasal angiofibroma in a horse.

This study examines a case of a 34-year-old horse that presented a rare tumor, known as angiofibroma, in the nasal area, which persisted even after attempts at partial removal. The diagnosis was confirmed through various tests after the horse was euthanized.

Case Presentation

• The horse in the study was a 34-year-old Haflinger gelding. It had a swelling or tumor in the nose, which despite being partly removed, resumed growth.
• The mass was unilateral, meaning it was present on only one side of the horse’s body, and expansile, indicating that it’s able to expand or stretch out.
• After the horse was euthanized, a detailed examination was done, revealing a large tumor originating from the left caudal maxillary sinus (an area at the back of the nasal cavity). The tumor completely filled the left nasal cavity.

Diagnostic Methods

• Radiological examination was done, which involved using X-rays to image the tissues and structures inside the nose. This helped in identifying the location, size, and possible nature of the tumor.
• A macroscopic examination, which involves visually inspecting the tumor directly, was also performed.
• Additionally, histopathology, the microscopic study of disease in tissues, was used to study the tumor. It turned out to be a neoplasm (a new and abnormal growth of tissue), which was not densely populated with cells but was highly vascular, meaning it had many blood vessels running through it.
• The tumour was made up of a loose network of spindle cells (which are elongated cells) and collagen fibres.

Immunohistochemistry and Final Diagnosis

• Immunohistochemistry, a method that uses antibodies to detect specific proteins in cells, was used. The spindle cells of the tumor positively reacted to alpha-smooth muscle actin (a protein present in muscle cells) and, to a lesser extent, vimentin (a protein associated with connective tissue formation).
• The endothelial cells, which line the blood vessels, showed positive reaction for factor VIII-related antigen, a protein involved in blood clotting.
• Based on these test results, and by comparing them with previous known cases in dogs and humans, the tumor was finally diagnosed as an angiofibroma.