Frontal sinus cells: Identification, prevalence, and association with frontal sinus mucosal thickening

Background: Frontal sinus cells (FSCs) are thought to be a potential cause of narrowing of frontal recess outflow. It remains unclear if FSCs are associated with frontal sinus mucosal thickening and chronic rhinosinusitis. The goal of the current study is to determine the prevalence of FSCs and their association with frontal sinus mucosal thickening. Methods: All adult patients undergoing computed tomography (CT) scans of the paranasal sinuses at our institution between February and October 2010 were reviewed. All CT scans were evaluated for the presence of FSC (types 1-4) and association with frontal mucosal thickening. The secondary outcome measure was to examine interrater agreement between two raters who independently evaluated all CT scans. Results: Analysis of 399 CT scans was performed with 71 scans excluded. The proportion of patients with FSC type 1 was 26%, 6.4% was type 2 cells, 2.1% was type 3 cells, and 0% was type 4 cells. The odds ratio of mucosal thickening for type 1 FSCs was 15.9 (95% CI, 9.8 -25.7), type 2 was 13.7 (95% CI, 6.7-27.8), and type 3 was 9.5 (95% CI, 3.0 -30.2). Interrater agreement for the evaluation of mucosal thickening was high (kappa, 0.69-0.76; p = 0.001). Agreement for the presence or absence of FSCs was moderate (kappa, 0.392; p = 0.001). Conclusion: There is a significant association of frontal sinus mucosal thickening with the presence of FSCs. Independent raters have moderate agreement when identifying the presence and type of FSCs.