Association of human papillomavirus 7 with warts in toe webs

Background There have been no studies on the prevalence of types of human papillomavirus (HPV) in cutaneous warts that focus on warts in toe webs (WTW). There is no documented association between HPV 7 and WTW. Objectives To explore the clinical and histopathological features of WTW, and the distribution of HPV genotypes in patients with WTW. Methods The study group consisted of 20 patients with WTW; 31 patients with typical verruca vulgaris (VV) were enrolled as the disease control group, and 53 patients with tinea pedis and 48 healthy volunteers were enrolled as the disease‐negative control group. Tissue specimens were analysed for clinical and histological features and distribution of HPV genotypes. Polymerase chain reaction (PCR)‐based direct sequencing, TA cloning and type‐specific PCR (TS‐PCR) were performed in the WTW and VV groups. Interdigital scale specimens from patients with tinea pedis and from healthy volunteers were analysed for HPV DNA by nested PCR and TS‐PCR (HPV 7). Results All the patients with WTW were male and nearly all were immunocompetent; their mean age was 41 ± 10 years. The lesions presented mainly as soft, friable and vegetating clusters. HPV 7 was the predominant genotype in WTW with a frequency of 80% (16/20). Fourteen specimens were taken for histopathological examination. The most frequent histological results (seven out of 14) revealed characteristics of HPV 7 infections such as heavily stained cells containing medium‐sized keratohyaline granules and a pronounced hyperkeratosis with parakeratosis. TA cloning showed that the sequence shared 90% or more homology with the HPV genotype in direct sequencing. No HPV 7 DNA was found in the scales taken from toe webs without warts. Conclusions This is the first study evaluating the prevalence of HPV types in WTW and the first report of the association between HPV 7 and specific subgroups of patients with warts.