Use of fluorescence in situ hybridization to detect Felis catus papillomavirus type 2 in feline Bowenoid in situ carcinomas.

OBJECTIVES: Papillomaviruses (PVs) are ubiquitous host- and site-specific viruses. PV infections in cats are associated with oral papillomas, viral plaques, Bowenoid in situ carcinomas (BISCs), squamous cell carcinomas and sarcoids; this association is primarily based on PCR detection of PV DNA within said lesions. PV DNA is frequently detectable on normal feline skin; thus, it is possible that some of the implicated DNA is commensal rather than associated with lesion formation. Therefore, the aim of the present study was to use fluorescence in situ hybridization (FISH) to localize PV DNA within feline BISCs, to provide additional evidence that PV infection may influence the development of these neoplasms. METHODS: FISH probes targeting Felis catus papillomavirus type 2 (FcaPV2) DNA were used to localize FcaPV2 DNA within 42 BISCs from which FcaPV2 DNA had previously been amplified via PCR. RESULTS: Fifteen of 42 BISC lesions (35.7%) demonstrated intralesional FcaPV2 using FISH. Probe annealing was predominantly located within the nuclei of koilocytes found in the upper strata of the epidermis. Probes were typically scattered multifocally within the lesions; most commonly this was near the periphery of the BISCs. CONCLUSIONS AND RELEVANCE: These results confirm that a proportion of BISCs contain FcaPV2 DNA. These results further support a causative association between FcaPV2 and BISCs in cats.

Papillomavirus-associated multicentric squamous cell carcinoma in situ in a cat: an unusually extensive and progressive case with subsequent metastasis.

BACKGROUND: Multicentric squamous cell carcinoma in situ (MSCCIS) is an uncommon cutaneous disease of middle-aged to older cats, with some cases being linked to papillomavirus infection. The disease course is usually benign. Initial eruption of multifocal, pigmented, hyperkeratotic plaques is typical, with gradual progression to thickly crusted ulcerative lesions. ANIMAL: A 5-year-old male neutered Devon rex cat in apparent good health was initially presented with a 16 month history of over 40 nonpruritic dorsally distributed hyperpigmented patches. Lesions progressed gradually over 2 years to larger, more pigmented, crusted plaques and ulcerated nodules. At 7 years of age the cat developed neurological signs and systemic illness and was euthanized. METHODS AND RESULTS: Initial skin histopathology revealed discrete regions of epidermal and follicular epithelial hyperplasia, with moderate numbers of apoptotic keratinocytes, and mild focal epithelial dysplasia. A diagnosis of erythema multiforme was considered; feline herpesvirus-1 immunohistochemistry was negative. Repeat histopathology 22 months after initial presentation confirmed MSCCIS with foci of invasive squamous cell carcinoma (SCC). Postmortem examination 1 month later revealed SCC within the thoracic wall, lungs and vessels of the thoracic spinal cord and heart base, presumed to be metastases from skin lesions. Fluorescent in situ hybridization of initial and later histopathology samples was positive for Felis domesticus papillomavirus type 2. Immunoreactivity of p16 was prominent within early and late cutaneous lesions and internal SCCs. CONCLUSIONS: This case represents an unusual presentation of papillomavirus-associated MSCCIS with extensive lesions, atypical initial histopathology and progression to SCC with distant metastases.