Detection of HPV by in situ hybridization in thin-layer (ThinPrep) cervicovaginal samples

We have studied an automated in situ hybridization (ISH) method as a possible alternative approach for detecting high-risk human papillomavirus (HPV) in monolayer (ThinPrep) cervico-vaginal samples, comparing the results with those obtained by polymerase chain reaction (PCR) using consensus primers and studying the relationship between the ISH staining pattern and the viral integration in HPV 16-positive cases. Eighty atypical squamous cells of undetermined significance (ASCUS) and low-grade squamous intraepithelial lesion (LSIL) cases were used for our purposes. The patients were monitored through periodic cytologies. ISH with was performed with an automated Ventana System, analysis by PCR was performed with consensus primers and integration of HPV16 was performed by realtime PCR analyzing E2 and E6 genes. Additionally, 27 HSIL cases were also studied to observe the ISH staining patterns. HPV infection was detected by ISH in 21.7% of the ASCUS cases and 55.8% of the LSIL cases. Two distinct staining patterns were observed: multipunctated (MP) and diffuse (DI). In some cases, a mixed pattern (MP + DI) was observed and these cases were considered as MP. The MP pattern increased with the degree of lesion and seemed to have a prognostic value in ASCUS/LSIL cases. The lesion in MP pattern cases persisted throughout the entire study in 77% of cases, whereas in cases with a DI staining pattern, only 41% of them showed persistence of the lesion (p <0.001). No correlation was found between HPV integration and the ISH staining pattern. Given the lower sensitivity and negative predictive value of ISH and its incapacity to demonstrate the integration of high-risk HPV in ASCUS and LSIL cases using liquid-based cytology, we do not recommend this technique for the triage of ASCUS and LSIL cases.