A case of salivary duct carcinoma of the buccal minor salivary gland

Abstract

Salivary duct carcinoma (SDC) that occurs in the oral cavity in the minor salivary glands is relatively rare. Here, we report a case of SDC arising from the buccal minor salivary glands. An 83-year-old man with a mass in the right buccal mucosa was referred to our department for detailed examination and treatment. As no metastatic lesions were found at other sites, SDC was suspected, and cT4aN0M0: Stage IVa was diagnosed in the right buccal mucosa. Subsequently, we performed tracheostomy, tumor resection, mandibular resection, reconstruction with a pectoralis major flap, and split-thickness skin graft under general anesthesia. Histological findings revealed formation of small alveolar clusters in the tumor with invasive proliferation in the surrounding tissue; keratinization was unclear. The findings indicated a glandular malignancy. Histologically, the tumor cells were strongly positive for HER2, AR, and GCDFP-15. Therefore, we diagnosed this tumor as an SDC. The patient is alive without recurrence or metastasis 29 months after surgery. As SDC is rare, especially in the minor salivary glands, the prognosis is poor, and the treatment not established. Hence, studies of accumulated cases are necessary for establishing adequate treatment for SDC of the head and neck region.