Analysis of the Risk of Neoplasm and Malignancy of Salivary Gland Neoplasm of Uncertain Malignant Potential (SUMP): From the Perspective of Cytomorphological Subgroups.

Objectives: This study aimed to investigate the risk of neoplasm (RON) and the risk of malignancy (ROM) in cases diagnosed as salivary gland neoplasm of uncertain malignant potential (SUMP), with subclassification based on cytomorphologic features. Methods: A retrospective review was conducted on salivary gland fine-needle aspiration (FNA) specimens diagnosed as SUMP between 2018 and 2022 in a tertiary care setting. Each case was re-evaluated by two pathologists and subclassified into basaloid, oncocytic, or clear cell/other categories according to the dominant cytomorphologic pattern. RON and ROM were calculated for the overall SUMP category and for each cytomorphologic subgroup. Results: Among 41 SUMP cases, the basaloid subtype was the most common (70.7%), followed by the oncocytic (19.5%) and the clear cell/others (9.8%). Histopathological confirmation was available in 65.9% of cases, all of which were neoplastic, resulting in a RON of 100%. The overall ROM was 29.6%. The ROMs by subgroup were 25% for basaloid, 40% for oncocytic, and 50% for clear cell/others. Pleomorphic adenoma was the most frequently encountered benign neoplasm (33.3%), and basal cell carcinoma was the most common malignant diagnosis (18.5%). The majority of malignant cases (87.5%) were located in the parotid gland. Conclusion: This study confirms the consistently high neoplastic potential of SUMP lesions and highlights the variation in malignancy risk among different cytomorphologic subtypes. Although the ROM differed among the subgroups, they all demonstrated clinical relevance, supporting the utility of cytomorphologic subclassification in salivary gland cytopathology. These findings may contribute to more refined risk assessment and patient management within the Milan System framework.