Clear cell carcinoma of the hard palate: A case report

Clear cell carcinoma (CCC) is a rare malignant tumor that represents less than 1% of all malignant tumors in the salivary glands. The term CCC was officially defined in the fourth edition of the World Health Organization classification of salivary tumors in 2017. Herein, we report a case of CCC arising in the hard palate of an 85-year-old man. The lesion was clinically suspected to be salivary gland tumor, and was resected under general anesthesia. Histopathologically, the tumor consisted of clear cells containing diastase-digestive PAS-positive granules without mucin. Immunohistochemically, the tumor cells were positive for cytokeratin and epithelial membrane antigen, but did not react with myoepithelial differentiation markers. Additional imaging techniques (computed tomography, magnetic resonance imaging, and positron emission tomography) were used to examine the lesion. No metastatic lesions were observed in other regions of the body. Thus, based on the histopathological and immunohistochemical findings and the results of the imaging tests, the tumor was finally diagnosed as a CCC. No evidence of recurrence or metastasis was noted after surgery.