Intraductal carcinoma of the retromolar trigone found with elevated serum CEA and CA19-9 levels: a case report

Abstract

Intraductal carcinoma (IDC) is a rare salivary gland tumor, classified according to the 4th WHO Classification of Head and Neck Tumors in 2017. The tumor affects the parotid gland much more frequently than the minor salivary glands. It’s often asymptomatic. We report a case of IDC of the left retromolar trigon occurring in an 81-year-old woman. She was diagnosed with high serum CEA and CA19-9 at a medical examination. Examinations of her gastrointestinal tract, lungs, and mammary glands were conducted, resulting in no abnormal findings. FDG-PET showed abnormal uptake only in the left retromolar trigon, and a painless mass was observed. A biopsy of this tumor indicated it was likely a low-grade salivary gland tumor. The tumor was completely removed, along with sufficient margins. Histological examination revealed that the lesion was composed of alveolar nests showing an expanded duct-like structure surrounded by an intact myoepithelial layer, with no evidence of infiltration. The final diagnosis was IDC. The postoperative course was uneventful and the patient’s serum CEA and CA19-9 levels decreased to within normal range. We believe that serum CEA and CA19-9 levels could be used for the diagnosis and evaluation of therapeutic effect for this tumor.