Atypical squamous metaplastic cells: reproducibility, outcome, and diagnostic features on ThinPrep Pap test

Area of Science:

• Cytopathology
• Gynecologic Pathology

Background:

• Atypical squamous metaplastic (ASM) cells are frequently associated with high-grade squamous intraepithelial lesions (HGSIL).
• The diagnostic accuracy and follow-up of ASM cases require further investigation.

Purpose of the Study:

• To evaluate the diagnostic reproducibility of atypical squamous metaplastic (ASM) cell diagnoses.
• To assess the biopsy follow-up results for cases initially diagnosed with ASM.

Main Methods:

• A review of 180 patients with ASM diagnoses between January and September 1998.
• 147 patients underwent subsequent biopsies, with results tallied.
• 20 cases were re-examined in a blinded manner to assess inter- and intraobserver agreement.

Main Results:

• Of 147 biopsies, 44.2% revealed HGSIL, 17.7% showed low-grade squamous intraepithelial lesion (LSIL), and 38.1% were benign.
• Individual diagnostic consistency was 50% (8/16), and overall agreement was 20% (13/64).

Conclusions:

• Approximately 62% of cytologically diagnosed ASM cases were associated with squamous intraepithelial lesions (SIL), predominantly HGSIL, upon biopsy.
• The findings emphasize the clinical significance of ASM but also reveal poor diagnostic reproducibility.
• Refined diagnostic criteria, continuing education, and second opinions are recommended to improve accuracy.