Tumors of the Sublingual Gland: a National Clinicopathologic Study of 29 Cases

Tumors of the salivary glands are a heterogeneous group of diseases most often originating in the major salivary glands. Only a minor proportion of mainly malignant tumors arise in the sublingual gland. Due to the rarity of sublingual gland tumors (SGTs), little is known about the clinicopathologic characteristics, prognostic factors, and clinical course. We present a large national series of histopathologically revised SGTs from the past 35 years in Denmark with clinicopathologic correlation. Twenty nine cases were identified, of which 96.6 % were malignant and 16/28 (57.1 %) were adenoid cystic carcinomas (ACC). Patient demography was similar to salivary gland tumors in other locations. All fine needle aspiration cytologies (FNACs) interpreted as benign were from ACCs. Metastatic disease was found in 12.5 % of ACCs at diagnosis with one third of all ACC patients having metastases at the end of follow-up. Stage >II and T-stage >2 were significantly associated with shortened disease-specific survival (DSS) (p = 0.005 and <0.001, respectively), whereas perineural invasion and involved margins was not. No parameters were associated with disease-free survival. In conclusion, the majority of SGTs are malignant, most frequently ACC with a high rate of metastatic spread. The diagnostic value of FNAC in SGTs seems inferior to what is found for other major salivary glands. DSS is determined by stage and T-stage and not by histopathological parameters. International collaboration is warranted to confirm and elaborate these findings in larger materials.