Vacuolated parabasal cells in Papanicolaou smears are cellular changes
caused by human papillomavirus 16 infection
Abstract
In cervical cancer screening, cytology is used as a triage test to refer
high-risk human papillomavirus (HR-HPV)-positive women for colposcopy,
but its accuracy is inadequate. The present study aimed to demonstrate
that the presence of atypical cells with large vacuoles in the cytoplasm
of parabasal cells, referred to as vacuolated parabasal cells (VPCs),
observed in the Pap smears of HPV-positive women is associated with
specific HPV genotypes. Among 2175 patients, 310 with a single HR-HPV
infection and cytological diagnosis of high-grade squamous
intraepithelial lesions (HSIL) or atypical squamous cells not excluding
HSIL (ASC-H) were included, of which 86 were infected with HPV16. Biopsy
results revealed that 69 (80.2%) patients had cervical intraepithelial
neoplasia Grade 2 or higher (CIN2+). VPCs were found in 47 (54.7%) of
HPV16-infected cases, indicating a significant increase of VPCs in
HPV16-infected cases ( p < 0.01). Episomal HPV16 load
was quantified in 142 VPCs and 156 HSIL (ASC-H) cells using LBC samples
from five patients, with a median of 987 copies in VPCs, significantly
higher than those in HSIL (ASC-H) cells (176 copies; p
< 0.001). VPCs in Pap specimens were identified not only as
cells altered by HPV16 infection but also as CIN2+-derived cells and
HPV16-producing cells.