Background
Salivary gland aspiration cytology is useful in preoperative management of patients but remains challenging due to extensive morphologic overlap of some tumors limiting the ability to always determine the presence of malignancy. In response to this challenge, there has been increasing drive to develop a risk-based categorization scheme for salivary gland aspirates. Herein we examine the interobserver variability of one such pattern and risk-based system.
Methods
Select smears and cell block sections from 50 salivary gland aspirates from two large academic centers were digitally imaged. These scanned slides were independently and blindly reviewed by four cytopathologists and each aspirate was assigned to one of the proposed pattern-based categories if it was considered neoplastic by the observer. Interobserver agreement was scored and aggregated risks of malignancy calculated for cases with available surgical follow-up.
Results
42 (84%) were considered neoplastic by at least two observers and scored for interobserver agreement. 23.8% (10 of 42) had uniform agreement, 33.3% (14 of 42) majority agreement, and 11.9% (5 of 42) divided agreement. Only 21.4% (9 of 42) had minimal agreement and 9.5% (4 of 42) had no agreement. Condensation of similar categories was able to improve interobserver agreement and still maintain stratified risk of malignancy.
Conclusions
This proposed pattern-based risk stratification scheme, which could be implemented with the forthcoming Milan System, has good overall interobserver agreement and successfully stratifies risk of malignancy. Some simplification is possible to make the system easier to use and improve interobserver agreement while maintaining stratification of risk.