HPV42 – a human papillomavirus classified as a low‐risk type with oncogenic potential

Human papillomavirus (HPV) type 42 is a rare HPV type currently classified as "low-risk" and belongs to the alpha genus. It has primarily been detected in benign vulvar papillomas and is predominantly associated with benign lesions such as anogenital warts. However, in very rare cases, HPV42 has also been identified in invasive genital tumors, particularly cervical carcinomas. In the case series presented here, HPV42 was detected in anogenital warts, a digital squamous cell carcinoma in situ, and a lymphogenously metastasized digital papillary adenocarcinoma (DPA). In the latter tumor entity, HPV42 was recently identified as the potential causative agent. Depending on the infected cell population, HPV42 can give rise to both benign lesions (anogenital warts and the rare cervicovaginal "seborrheic keratosis-like" lesion) and malignant lesions (anogenital and digital carcinomas, as well as the highly aggressive DPA). HPV42 can therefore be considered as potentially carcinogenic. With the currently available nonavalent HPV vaccine over 90% of HPV-related tumors and anogenital warts can be prevented, but not HPV42-induced lesions. These tumors will therefore not be suppressed by the current vaccination programs, even not in countries with high vaccination rates.