Optimizing the pre-analytical phase for accurate HPV detection in skin disorders: insights from a cutaneous warts case study

BACKGROUND: In previous years, several cutaneous disorders have been associated with human papillomavirus (HPV); however, the exact role of HPV remains largely unknown. The lack of optimization and standardization of the pre-analytical phase forms a major obstacle. The aim of this study was to develop an accurate/patient-friendly sampling method for skin disorders, with cutaneous warts as a case study. METHODS: Various sample processing techniques, pre-treatment protocols and DNA extraction methods were evaluated. Several sampling methods were examined, that is, skin scrapings, swabs and a tape-based method. Quantification of DNA yield was achieved by beta-globin real-time polymerase chain reaction (qPCR), and a wart-associated HPV genotyping qPCR was used to determine the HPV prevalence. RESULTS: All samples tested positive for beta-globin. Skin scrapings had significantly higher yield than both swab and tape-based methods (p < 0.01), the latter two did not significantly differ from each other (p > 0.05). No significant difference in DNA yield was found between cotton and flocked swabs (p > 0.05). All swabs were HPV positive, and although there were some discrepancies in HPV prevalence between both swabs, an overall good strength of agreement was found [κ = 0.77, 95% CI (0.71–0.83)]. CONCLUSION: Although skin scrapings produced the highest DNA yield, patient discomfort was an important limitation of this method. Considering that in combination with our optimized DNA extraction procedure, all samples gave valid results with the less invasive swab methods preferred. Standardization of the pre-analytical phase is the first step in establishing a link between HPV and specific skin disorders and may have significant downstream diagnostic as well as therapeutic implications.