High-grade squamous intraepithelial lesion cervicovaginal paps with negative high-risk HPV testing, a prospective study with histological follow-up.

Background: High-risk human papillomavirus (hrHPV) testing has become integral in the screening and treatment protocols for cervical neoplasia. Stand-alone HPV testing is advocated as a screening tool for cervical neoplasia. However, negative hrHPV tests with diagnosis of high-grade squamous intraepithelial lesion or worse (≥HSIL) have been reported. We report our experience with paps diagnosed as HSIL, negative hrHPV testing, and subsequent follow-up.

Methods: Of 303 women with HSIL diagnosed on ThinPrep pap between 2019 and 2023, 84 (28%) were tested for hrHPV by Roche Cobas. Repeat testing was performed at a referral center. Immunohistochemistry (IHC) for p16 was performed on follow-up biopsies and hrHPV in-situ hybridization.

Results: Of 84 HSIL cases, 8 were hrHPV negative. Follow-up biopsies available in 7 cases were ≥HSIL (1 with invasive squamous cell carcinoma, 1 endocervical adenocarcinoma in situ). Follow-up HSIL was found on additional cases of HPV negative atypical glandular cells favor neoplastic and atypical squamous cells favor HSIL. IHC for p16 was positive on all biopsies. hrHPV FISH was negative.

Conclusions: Our experience with hrHPV testing by Roche Cobas demonstrates that some morphologically diagnostic HSIL paps are hrHPV negative: 8.3% of HSIL paps with subsequent histological HSIL were HPV negative. The index case caused concern among our clinical colleagues. Positive staining for p16 is highly suggestive of HPV induced disease. Possible reasons for negative hrHPV testing could include non-hrHPV types, low HPV DNA levels, or HPV types not included in the Cobas testing panel.