Prevalence and distribution of 15 high-risk human papillomavirus types in squamous cell carcinoma of the scrotum.

Which subtype(s) of high-risk human papillomavirus (hrHPV) are involved in squamous cell carcinoma (SCC) of the scrotum is unknown. Twenty-seven cases of SCC of the scrotum were retrieved, and all 15 subtypes of hrHPV and their viral loads were assessed using multiplex real-time polymerase chain reaction. The results were correlated with the histopathologic features, p16 expression, and in situ hybridization for hrHPV. hrHPV was identified in 18 (67%) of 27 of the cases, including HPV16 (n=8), HPV35 (n=7), HPV31 (n=5), HPV59 (n=5), HPV33 (n=3), HPV18 (n=2), HPV51 (n=2), HPV39 (n=1), HPV56 (n=1), and HPV82 (n=1). Of the 18 cases, 10 (56%) were infected by multiple hrHPV subtypes. In situ carcinomas had higher viral loads than invasive (50M versus 2M in average). The average age of HPV-positive and -negative cases was similar, 55 and 51, respectively. Of 11 cases of invasive carcinoma, 5 (45%) were positive for hrHPV versus 13 of 16 (81%) of in situ carcinomas. The highest proportion of hrHPV-positive cases was seen in basaloid type (7/7; 100%) and warty type (4/4; 100%), followed by usual type (7/16; 44%). Of 18 of the HPV-positive cases, 9 (50%) were also positive for p16 by immunohistochemistry and 6 of 18 (33%) were positive by in situ hybridization. Similar to SCC of the vulva and penis, the most frequently HPV-positive tumors are basaloid and warty types. However, a proportion of SCC usual type are also positive for hrHPV. Our results show that 8 (44%) of 18 of cases are associated with hrHPV subtypes other than 16 and 18. Additionally, 7 (70%) of 10 of hrHPV16/18-positive cases are coinfected with other subtypes.