Human papillomavirus typing of warts and response to cryotherapy.

Background  Cutaneous warts are common and caused by a number of different types of human papillomaviruses (HPVs). Objective  The aim of this study was to investigate the HPV types causing common warts and to determine any association between the HPV type and the duration of warts and response to cryotherapy. Methods  Eighty wart samples from 76 immunocompetent patients were taken from warts by paring prior to cryotherapy and analysed by in situ hybridization (ISH) with HPV probes specific to HPV 1, 2, 3, 4, 7, 10 and 57 and PCR analysis using degenerate cutaneous HPV primers with subsequent DNA sequencing. Each patient's details, including site, duration and response of the wart to cryotherapy were recorded. Cryotherapy was performed at 2 week intervals for a maximum of 12 weeks. Results  An HPV type was identified in 65 samples. The majority of warts (58 samples) were typed as HPV 2/27/57 by ISH and/or PCR. Three of the 18 samples that were HPV negative with ISH were HPV positive by PCR. Response to treatment did not correlate with HPV type, duration or location. In the 21 wart parings taken from patients aged 16 and under, response to treatment did not correlate with HPV type but warts of shorter duration were more likely to resolve with cryotherapy treatment than longer standing lesions. Conclusion  This study demonstrates that HPV type can be determined from wart parings. HPV-2 related viruses are the prevalent HPV types causing common warts on the hands and feet in this population.