Milan System Salivary Gland Neoplasm of Uncertain Malignant Potential: Males and 30–69-year-olds have the Highest Risk of Malignancy

Summary: Introduction: Salivary gland neoplasm of uncertain malignant potential (SUMP) is diagnostically challenging category of the Milan System for Reporting Salivary Gland Cytopathology (Table 1). Salivary gland tumors are slightly more common in female population, but males have a higher risk of malignancy, and the risk is the highest in the sixth and seventh decades of life. Our study aims to evaluate SUMP category in our institution and analyze how sex and age affect the outcome. Materials and Methods: Search from database system was done to collect all salivary gland FNAs categorized as SUMP between January 1, 2018, and December 31, 2022, at the Department of Pathology, Fimlab Laboratories, Tampere, Finland. Follow-ups for SUMP cases were collected until May 31, 2023, if available. Upper and lower bounds of the Risk of Malignancy (ROM) and Risk of Neoplasm (RON) were calculated. In addition, the impact of sex and age was analyzed. Results: Out of 1157 FNAs, 100 FNAs were categorized as SUMP from 52 females and 33 males. Of these SUMP cases, 69 (69.0%) had histological verification (Table 2) and there were 26 repeated FNAs (Table 3). Upper and lower bound ROMs were 26.9% and 21.2% in male group vs. 16.2% and 11.5% in female group, respectively. RONs were 100.0% and 78.8% in male group vs. 89.2% and 63.5% in female group. ROMs were 0.0% and 0.0% in the 20-29 age group, 25.0% and 22.2% in the 30-69 age group, and 19.2% and 11.4% in the 70+ age group. Conclusions: In our series, ROM varies in sex and age groups with the highest values in 30-69 age group and males, not in agreement with salivary gland tumor epidemiology. There might be overdiagnosis in certain benign entities namely nodular oncocytic hyperplasia and benign tumors to name pleomorphic adenoma in our practice.