Clinical, histopathological, and epidemiological characterisation of accessory parotid gland tumours in relation to parotid and submandibular gland tumours: observations based on 2653 cases of the Polish Salivary Network Database.

Salivary gland tumours comprise one of the most complex and rare groups of heterogeneous lesions encountered in oral pathology. Large clinical and population-based epidemiological studies are inherently limited. This multicentre prospective study was conducted between 2017 and 2021 using the Polish Salivary Network Database (PSND). A dataset of 2653 cases of salivary gland tumours was analysed, focusing on the submandibular gland (n = 173), accessory parotid gland (n = 100), and parotid gland (n = 2375). Epidemiological and pathological factors were considered to identify the risk of malignancy and differences between tumours of the submandibular, parotid, and accessory parotid glands. A significant difference was observed in the median age of patients with tumours of the submandibular (50.5 years) and accessory parotid glands (51.5 years) compared with that of patients with parotid gland tumours (60.0 years) (p < 0.001). Factors such as tobacco usage (p < 0.001) and place of residence (p = 0.015) were associated with these differences. Sex was not a differentiating factor in the risk of malignancy. In females, 106/173 patients had tumours in the submandibular gland, 61/100 had tumours in the accessory parotid, and 1282/2375 had tumours in the parotid. In males, 67/173 had tumours in the submandibular gland, 39/100 had tumours in the accessory parotid, and 1093/2375 had tumours in the parotid. Significant differences were found in submandibular and parotid tumour locations between village and city inhabitants (p = 0.016). The nature of tumours located in the parotid, comprising the superficial and deep lobes, was distinct in relation to accessory parotid tumours. Accessory parotid tumours exhibited more similarities to those originating in the submandibular region. These findings have the potential to impact future clinical approaches. However, additional validation studies are needed.