Coinfection with Different Feline Papillomaviruses in a Cat with Multicentric Squamous Cell Carcinoma In Situ

A 14-year-old neutered male domestic shorthair cat was evaluated for long-standing, non-pruritic, crusty skin lesions on the pinnae, neck, and ventral abdomen that had persisted for at least 4 years. The histopathological examination of biopsies from the neck and abdomen revealed multicentric squamous cell carcinoma in situ confined to the epidermis. Papillomavirus diagnostics on ear crusts using PCR, rolling circle amplification (RCA), and next-generation sequencing (NGS) identified coinfection with Felis catus papillomavirus type 7 (FcPV7) and a putative novel feline papillomavirus type. This is the first reported case of multicentric carcinoma in situ with coinfection by these two papillomaviruses. The condition was successfully managed medically with topical imiquimod cream applied twice weekly for 3 months, resulting in complete clinical remission. Over 1.5 years of follow-up, they remained well. Two mild recurrences on the dorsal neck were effectively controlled with a short repeat course of imiquimod. This case report documents coinfection with different feline papillomavirus types in a cat and highlights an efficacious, practical, non-surgical treatment with the topical immunomodulatory imiquimod cream.