Submandibular adenoid cystic carcinoma with multiple spinal metastases but without pulmonary metastases at the initial diagnosis : A case report

Abstract

Submandibular gland tumors occur less frequently than parotid gland tumors but account for a higher proportion of malignant tumors. The most common subtype of submandibular gland tumor is adenoid cystic carcinoma. Clinically, ACC is characterized by slow growth and a lack of early symptoms; however, ACC tends to invade the soft tissues surrounding the submandibular gland and adjacent perineural tissues, resulting in extensive extension. ACC also easily metastasizes to the lungs and bones, and has a poor prognosis. The patient was a 50-year-old woman. During an outpatient visit, swelling was observed in the right submandibular region, and a malignant tumor of the submandibular gland was diagnosed using neck ultrasound and fine-needle cytology. CT imaging showed no signs of cervical lymph node metastasis or lung metastasis, but PET-CT revealed high FDG accumulation in the spine and trunk bones throughout the body, suggesting multiple bone metastases throughout the body. No metastasis was observed in the lungs. Right submandibular adenectomy was performed to make a definitive diagnosis, and a diagnosis of submandibular ACC was confirmed. While bone metastasis during follow-up is a common mode of metastasis of the submandibular ACC, the presence of multiple bone metastases throughout the body at the time of the initial diagnosis is rare.