Atypical squamous cells, cannot exclude high-grade squamous intraepithelial lesion - Cytohistologic correlation study with diagnostic pitfalls

Objective In the current study, we explore the diagnostic parameters and pitfalls in the follow-up of 123 cases of Pap Smears diagnosed as high-grade atypical squamous cells (ASC-H) at our institution. Study Design A computer database search was performed from the archives of the Ottawa Hospital Cytopathology Service for cases diagnosed with ASC-H between January 2003 and July 2005. Results Follow-up of the 123 cases of ASC-H showed high grade squamous intraepithelial lesion (HSIL) in 73 patients (59.4%), low grade squamous intraepithelial lesion (LSIL) in 11 (8.9%), immature squamous metaplasia in 23 (18.7%), reactive squamous cell changes in 12 (9.8%), benign glandular lesions (endocervical atypia, degenerated glandular cells) in 2 (1.6%) and atrophy in 2 (1.6%). In our study, 83 patients were younger than 40 years (65.1%). The remaining 40 patients (32.6%) were older than 40 years of age, and follow-up biopsies showed HSIL in 19 patients (47.5%.). Conclusion In our study, 59.4% of the cases at were diagnosed cytologically as ASC-H were found to have HSIL on subsequent biopsies. This correlation below the age of 40 years (65.1% vs. 47.5%). The cytopathologic feature most strongly associated with HSIL was the presence of coarse nuclear chromatin (84%).