P61: The presence of koilocytes in human actinic keratosis defines human papillomavirus 8 reactivation

Alex Gibbs,¹ Carlotta Olivero,¹ Huw Morgan,¹ Charlotte Lovatt,¹ Boris Shorning,¹ Lokapriya Anantham,¹ Gemma Davies,¹ Megan Williams,¹ Baki Agul,² Marisa Gariglio³ and Girish Patel¹

¹Cardiff University, Cardiff, UK; ²University of Cologne, Cologne, Germany; and ³Novara Medical School, Novara, Italy

The incidence of cutaneous squamous cell carcinoma (cSCC) has been increasing by 5% per annum, with 45 000 individuals having a new diagnosis of cSCC in England each year; within 1 year 25% will develop a further primary cSCC. For many, cSCC will have developed on the background of field cancerization (FC), characterized clinically by actinic keratoses (AK) and cSCC in situ. Multiple studies have identified that oncogenic human papillomavirus (HPV) genotypes may contribute to FC in immunocompromised individuals. In a previous study, our laboratory found that HPV8 could drive hair follicle junctional zone keratinocyte stem cells to recreate the pathological features of AK and determined HPV8 reactivation in an immunocompetent individual. In this study we sought to determine the frequency of HPV-associated AK in immunocompetent individuals. After regional ethics committee and National Health Service research and development approvals, 443 immunocompetent FC individuals consented for tissue samples to be analysed for evidence of HPV. Haematoxylin and eosin-labelled tissue sections were scanned and examined. A random sample of 79 tissues were examined in detail by analysis of DNA and immunohistochemistry. Overall 54% of tissue samples demonstrated the presence of koilocytosis within the epidermis. Within the representative sample set, HPV8 was detected in 97% (n = 42), using a highly sensitive and validated polymerase chain reaction (PCR) reverse hybridization assay method that identifies 25 separate β-HPV genotypes. In 60% (n = 25) of cases, HPV8 was the only β-HPV genotype identified. Consistent with the previously determined low detection rate, nested PCR detected HPV8 E6 in only 13% (n = 10/79). While labelling with the specific HPV8 E4 antibody identified cytoplasmic protein expression in only 12% (n = 5) of the samples. The presence of koiliocyte-like keratinocytes in AK was not associated with a significant difference in age, sex (Fisher’s exact test, nonsignificant), body location or other histological classifiers. The presence of koilocytes was associated with reduced DNA damage (H2AX labelling, P < 0.01), greater expression of p63 (P < 0.05) and STAT3 (P < 0.01). However, there was no difference in p53 labelling. Collectively, these findings support the pathogenic role of HPV8, a known oncogenic β-HPV genotype, in the pathogenesis of FC as previously described in immunocompromised individuals and now otherwise immunocompetent patients. The absence of any associated findings may account for why the presence of koilocyte-like keratinocytes and therefore HPV8 reactivation within human AK is under-reported.