High-grade squamous intraepithelial lesions and invasive carcinoma following the report of three negative Papanicolaou smears: screening failures or rapid progression?

The cytologic smears and histopathologic specimens of 18 patients developing cervical intraepithelial neoplasia 3 (CIN3) and two developing invasive squamous carcinoma following the report of at least three negative Papanicolaou tests were studied. A median number of 9.5 smears per patient procured over a median interval of 93.5 mo were reviewed. Twenty-eight (22.7%) of 123 reportedly negative smears revealed a squamous intraepithelial lesion (SIL), 17 (13.8%) were unsatisfactory, 14 (11.4%) lacked an endocervical component, and 37 (30.1%) were classified as atypical squamous cells of undetermined significance (ASQUS) on reexamination. Fourteen (50%) of 28 smears originally misclassified as negative contained fewer than 100 SIL cells and five (17.8%) were severely inflamed. One patient whose smears were misclassified as negative had an atrophic cervix, one had SIL cells primarily in thick sheets, and two had small CIN3 cells resembling squamous metaplasia. Six patients (30%) had a single false negative smear, seven (35%) had multiple false negative smears, seven (35%) had two or more unsatisfactory smears reported as negative, seven had at least two smears lacking an endocervical component, and six had at least two smears taken during pregnancy. Thirteen patients had abnormal smears classified as ASQUS or high-grade SIL (HSIL) but never had a specimen showing only a low-grade SIL (LSIL). This study demonstrates that early signs of SIL may be difficult to recognize cytologically and that poor quality specimens and inadequate sampling may contribute to false negative diagnoses.(ABSTRACT TRUNCATED AT 250 WORDS)