EcPV2 DNA in equine papillomas and in situ and invasive squamous cell carcinomas supports papillomavirus etiology

Equine penile papillomas, in situ carcinomas, and invasive carcinomas are hypothesized to belong to a continuum of papillomavirus-induced diseases. The former ones clinically present as small grey papules, while the latter 2 lesions are more hyperplasic or alternatively ulcerated. To test the hypothesis that these lesions are papillomavirus-induced, samples of 24 horses with characteristic clinical and histologic findings of penile papillomas or in situ or invasive squamous cell carcinomas were collected. As controls, 11 horses with various lesions--namely, Balanoposthitis (6 cases), melanoma (3 cases), follicular cyst (1 case), and amyloidosis (1 case)--were included. DNA was extracted and polymerase chain reaction applied to amplify papillomavirus DNA. The respective primers were designed to amplify DNA of the recently discovered equine papillomavirus EcPV2. All tested papilloma and squamous cell carcinoma samples were found to contain DNA of either of 2 previously published EcPV2 variants. Among the other samples 6 of 11 were found to contain EcPV2 DNA. To further support the findings and to determine where the papillomavirus DNA was located within the lesions, an in situ hybridization for the detection of EcPV2 DNA was established. The samples tested by this technique were found to clearly contain papillomavirus nucleic acid concentrated in the nucleus of the koilocytes. The findings of this study support previous data and the hypothesis that papillomaviruses induce the described penile lesions in horses.

Aberrant E-cadherin, beta-catenin, and glial fibrillary acidic protein (GFAP) expression in canine choroid plexus tumors

Expression of E-cadherin and beta-catenin has been widely studied in various human and canine epithelial tumors and has been correlated with dedifferentiation, invasiveness, and metastasis. Choroid plexus tumors (CPTs) are of epithelial origin, and the most important prognostic factor in human medicine is the tumor grade. Limited information is available regarding E-cadherin and beta-catenin expression in human CPTs, and no information is found in the veterinary literature. In the current study, 42 canine CPTs (19 choroid plexus papillomas and 23 choroid plexus carcinomas) were retrospectively reviewed, and the intensity and cellular staining pattern of E-cadherin and beta-catenin were correlated with histological features, paying special attention to grade, invasion, and metastasis. In addition, cytokeratin and glial fibrillary acidic protein (GFAP) antibodies were evaluated as markers for canine CPTs. It was found that loss of E-cadherin and beta-catenin expression was uncommon in canine CPTs. Rather, membranous expression of both molecules was increased in CPTs compared to normal choroid plexus (NCP), regardless of tumor grade. Additionally, aberrant cytoplasmic or nuclear expression of both E-cadherin and beta-catenin was often observed in CPTs. GFAP was frequently expressed in CPTs in contrast to NCP. None of these parameters were correlated with malignancy, and therefore, do not appear to be useful for prognostic information. Nevertheless, a panel of antibodies including E-cadherin and GFAP might be useful to support the diagnosis of CPTs and help to differentiate them from other tumors, such as ependymomas and metastatic epithelial tumors.