Verrucous hemangioma with pseudoepitheliomatous epidermal hyperplasia in an adult horse.

This research article describes a previously under-documented skin tumor variant called verrucous hemangioma discovered in an adult horse, emphasizing the significance of a pathological study for early diagnosis and timely treatment.

Research Investigation and Methodology

• The study centered on an 8-year-old gelding (a neutered male horse) that had a unique skin lesion on its pastern (part of a horse’s foot). This unusual growth, described as warty and verrucous in nature, featured localized ulcerations.
• A histological examination was made–a study of the microscopic anatomy of the cells and tissues. The researchers discovered a growth in the dermal layer of the horse’s skin, composed of endothelial-layered capillaries and venules (small vessels connected to the capillaries). These were divided by a delicate stroma, a connective, supportive structure of the tumor composed of scant fibroblasts and collagen deposition.
• Pseudoepitheliomatous hyperplasia, a condition characterized by abnormal growth of the epithelial cells mimicking the downgrowth of squamous cell carcinoma, was also observed. The horse’s epidermis, the outer layer of skin, showed orthokeratotic hyperkeratosis–an overgrowth of keratin, a protein in skin cells.
• Immunohistochemistry, a process that uses antibodies to detect the presence of specific proteins in tissues, was utilized to establish the endothelial (blood-vessel related) origin of the tumor.

Findings and Diagnosis

• The combination of all these microscopic findings led to the definitive diagnosis of verrucous hemangioma with pseudoepitheliomatous hyperplasia. Verrucous hemangioma is a specific and rare type of skin tumor, and the occurrence of pseudoepitheliomatous hyperplasia alongside it was considered significant.
• The researchers emphasise that this is the first thorough report of such a case in an adult horse, marking a noteworthy contribution to the field of veterinary oncology.

Implications and Recommendations

• The research’s outcomes revealed not only new scientific data but also underscored the valuable role of pathological examinations in diagnosing skin tumors in horses. Specifically, it highlighted that investigating potential epithelial preneoplastic lesions could reveal underlying dermal neoplasia, a type of cancer.
• The discovery of this variant of skin tumor and its associated condition introduces a new aspect to be considered in the diagnosis and treatment of such diseases in horses, specifically adult ones. This could influence future consultation, care, and therapy of equine patients with similar symptoms.