Cutaneous papilloma associated with a novel papillomavirus sequence in a cat.

A 5-mm diameter mass developed on the nasal planum of a 4.5-y-old castrated male domestic shorthaired cat; the mass was raised ~2 mm above the surrounding skin. Histology revealed focal thickening of the epidermis with marked orthokeratosis. Many of the epidermal cells within the mass had prominent papillomavirus-induced changes. A diagnosis of a viral papilloma was made, and a DNA sequence from a novel papillomavirus type was amplified from the lesion. Although the sequence was most similar to other feline papillomavirus types, the low level of similarity was suggestive of a novel papillomavirus genus. There has been no recurrence of the mass or development of additional lesions in the 6 mo since the mass was removed. This is the third cutaneous papilloma reported in a cat; a putative feline papillomavirus type has not been identified previously within these lesions, to our knowledge. Our findings expand the range of lesions associated with papillomaviruses in cats and increase the number of papillomavirus types that infect cats.