False positive cervical smears: a cytometric and histological study

Area of Science:

• Gynecologic pathology
• Cytopathology
• Molecular pathology

Background:

• Exfoliative cytology of the cervix uteri is crucial for early detection but can yield false positive results.
• An average of 8.8% of cervical smears are false positives, leading to potential over-diagnosis and unnecessary interventions.

Purpose of the Study:

• To identify non-neoplastic causes of false positive cervical cytology results.
• To evaluate the utility of nuclear Feulgen-DNA measurements in clarifying ambiguous cytological findings.
• To reduce the rate of false positive cervical smear diagnoses through improved diagnostic methods.

Main Methods:

• Review of 170 false positive Papanicolaou-stained cervical smears and corresponding histological specimens.
• Histological re-examination to identify non-neoplastic changes.
• Nuclear Feulgen-DNA measurements using a single-cell algorithm (5c/9c exceeding events) to detect aneuploidy.

Main Results:

• Histological re-examination identified causes for false positives in 50% of cases, including inflammation, cellular changes, and human papilloma virus (HPV) infection (51.9%).
• In cases lacking histological explanation, DNA measurements revealed aneuploidy in 62.7% of specimens, with 23.1% showing signs of HPV infection.
• The combined approach of histological review and DNA measurement reduced the number of confirmed false positive diagnoses from 170 to 97.

Conclusions:

• Histological re-examination and DNA ploidy analysis are valuable tools for clarifying false positive cervical cytology results.
• DNA measurement is recommended for suspicious cervical smears to improve diagnostic accuracy and reduce false positives.
• Accurate diagnosis through these methods can prevent unnecessary patient anxiety and interventions.