Human papillomavirus infection and tumours of the anal canal: correlation of histology, PCR detection in paraffin sections and serology

Human papillomavirus infection is an important etiological factor in squamous cell carcinoma of the anus (SCCA). Different histological variants of anal carcinomas displaying squamous differentiation, previously classified as separate tumours, were recently reclassified as SCCA by the WHO. In our recent study the presence of HPV was detected by PCR in biopsy specimens of 42 different anal tumours, including SCCA and its histological variants (n=22), adenocarcinomas (n=5), tubulovillous adenomas (n=5) and anal condylomas (n=10). HR HPV16 (high risk-HR) was detected in 18 of SCCA specimens (81.8%). All histological variants, i.e. tumours with basaloid, squamous and mixed histological patterns, were represented among the HPV-positive cancers. Four tumours (18.2%) were HPV negative. Low-risk (LR) HPV types were not detected within the SCCA group. HPV16 was identified in one adenocarcinoma, while four cases were HPV negative. Two adenomas showed presence of HPV16; one showed simultaneous positivity for HPV33. The remaining three tumours were HPV negative. Seven anal condylomas (70%) were LR HPV 6 and/or 11 positive, while three were HPV negative. The presence of HR HPV types was not observed in anal condylomas. Our results provide further evidence in support of the etiological role of HR HPV infection in the development of SCCA regardless of its histological appearance.