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

Atypical squamous metaplastic (ASM) cells are associated with high-grade squamous intraepithelial lesions (HGSIL) in many cases. The reproducibility of the diagnosis and biopsy follow-up results of cases designated as ASM were studied at Women and Infants' Hospital of Rhode Island.

Of 180 patients with ASM who the authors examined from January 1, 1998 to September 30, 1998, 147 (81.7%) had subsequent biopsies. Results of the biopsies were tallied. Twenty cases were rescreened in a blinded fashion to determine intra- and interobserver agreement and to identify diagnostic features.

Sixty-five (44.2%) cases of ASM had HGSIL on biopsy, 26 (17.7%) had low-grade squamous intraepithelial lesion, and 56 cases (38.1%) were benign. Overall individual consistency is 8 of 16 (50%), and overall agreement is 13 of 64 (20%).

Sixty-two percent of cases designated as ASM cytologically were associated with SIL, primarily HGSIL, at biopsies. The findings underscore the importance of this subcategory of atypical squamous cells. However, poor reproducibility suggests the need for refined criteria and/or continuing education, and obtaining second opinion. Cancer (Cancer Cytopathol)