Feline bowenoid in situ carcinoma is also known as multicentric squamous cell carcinoma. It is a rare disease that tends to present as pigmented plaque. Histologic characteristics include marked epidermal hyperplasia and dysplasia. Papillomaviruses have been found to be associated with other cutaneous tumors, and in previous studies, as many as 47% of samples tested revealed viral antigens. In this study, polymerase chain reaction testing was used to identify viral DNA. Eighteen formal fixed samples and 6 controls were tested; papillomavirus was found in 11 of 18 samples and in none of the controls. Papillomavirus seems to be associated with this feline skin tumor. Furthermore, the papillomavirus sequences were closely related to human papillomavirus.

COMMENTARY: Studies are increasingly showing that these skin tumors are a malignant transformation of papillomavirus infection. Demodex infestations have been associated with lesion development, which tends to occur in old cats (>10 years) and most commonly involves thickly haired areas, especially pigmented areas. Some lesions develop cutaneous horns or can become verrucous, crusted, and ulcerated as they worsen. Atypical presentations of squamous cell carcinoma, bowenoid lesions may wax and wane-as a result, it can be hard to convince owners that biopsy is necessary. Diagnosis is often a surprise due to the unusual clinical presentation of the lesions. Retinoids have been inconsistently reported as helpful in treatment. Some owners may choose not to treat if the cat is unbothered by the lesions.

Detection of papillomaviral sequences in feline Bowenoid in situ carcinoma using consensus primers. Munday JS, Kiupel M, French AF, et al. Vet Dermatol 18:241-245, 2007.