Tracking Pleomorphic Adenoma Incidence Trends Over 47 Years: A Population-Based Study

To (1) track the incidence of pleomorphic adenomas (PAs) and (2) compare demographic and treatment trends in PAs over the last five decades in a single county.

Retrospective cohort of all patients with a pathologic diagnosis of nonrecurrent PA from January 1976 to December 2022.

Olmsted County, Minnesota.

Incidence was calculated per 100,000 persons/year and age and sex-adjusted to the US 2020 census data. Incidence trends were identified using Poisson rate regression models. Changes in clinical features of diagnosis were evaluated using Spearman rank correlation coefficient tests, Wilcoxon rank sum tests, and Kruskal-Wallis tests.

In total, 251 patients with PA were identified. The median age at diagnosis was 50.0 years with a slight female predominance (1.24:1). The adjusted incidence during this period is 4.79/100,000 person-years, increasing from 2.50 in 1976 to 1979 to 5.73/100,000 persons/year in 2020 to 2022. Less extensive surgery, including partial and superficial parotidectomies, increased significantly from 1976 to 2022, whereas total parotidectomies decreased (P < .0001). The number of patients who presented with an incidental imaging finding increased during this time period (P < .001), as did the age at diagnosis (45-51 years, P = .05) CONCLUSION: The average annual incidence of PAs in Olmsted County from 1976 to 2022 is higher than reported US estimates and has increased over the last five decades. The percentage of patients who presented with incidental imaging findings increased over this period, as did the age at diagnosis. These findings highlight modern imaging techniques and an aging population more willing to seek workup and treatment of a benign parotid mass.