Verrucous hemangioma with pseudoepitheliomatous epidermal hyperplasia in an adult horse.
Authors: Pérez-Écija A, Estepa J C, Barranco I, Rodríguez-Gómez I M, Mendoza F J, Gómez-Laguna J
Journal: Veterinary pathology
Summary
# Editorial Summary Verrucous haemangiomas represent a poorly characterised variant of equine skin neoplasia, with limited clinical and histopathological documentation in the literature until this 2014 case report. An 8-year-old gelding presented with a unilateral pastern lesion displaying a characteristic warty, verrucous surface with focal ulceration; histological examination revealed a dermal proliferation of capillaries and venules accompanied by pseudoepitheliomatous epidermal hyperplasia—a reactive epithelial thickening with irregular downgrowths that can mimic squamous cell carcinoma—alongside orthokeratotic hyperkeratosis. Immunohistochemical staining confirmed the endothelial origin of the proliferative tissue, establishing this as the first detailed description of verrucous haemangioma with pseudoepitheliomatous changes in an adult horse. The significance of this case lies in highlighting a diagnostic pitfall: the exuberant reactive epidermal response overlying a benign vascular tumour can closely resemble malignant epithelial disease, underscoring the critical importance of obtaining full-thickness biopsies and thorough histopathological evaluation when assessing any chronic or atypical skin lesion in the distal limb. Practitioners encountering warty or ulcerated pastern masses should maintain a broad differential and resist over-reliance on surface morphology alone.
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Practical Takeaways
- •Warty or verrucous pastern lesions require histopathological examination to definitively differentiate benign hemangiomas from squamous cell carcinoma, as epidermal hyperplasia can mimic malignancy
- •Pseudoepitheliomatous hyperplasia is a reactive benign process that should not be misdiagnosed as cancer based on histological appearance alone
- •Always submit epithelial skin lesions for pathological study rather than assuming diagnosis based on clinical appearance alone
Key Findings
- •First detailed description of verrucous hemangioma with pseudoepitheliomatous hyperplasia in an adult horse
- •Lesion presented as unilateral warty mass on pastern with focal ulcerations and orthokeratotic hyperkeratosis
- •Histopathology revealed dermal capillary and venule proliferation with reactive epithelial hyperplasia mimicking malignancy
- •Immunohistochemistry confirmed endothelial origin, distinguishing benign hemangioma from squamous cell carcinoma