Adenoid cystic carcinoma of maxillary sinus metastatic to the kidney: a case report and review of the literature

Adenoid cystic carcinoma (ACC) is a rare malignant tumor of minor salivary gland, accounting for less than 2% of all the head and neck malignancies. It is characterized as slow growth, long clinical course, local recurrences and distant metastases. Once ACC of primary site presents recurrence and distant metastasis, the prognosis is generally poor. Renal metastasis related to this cancer is relatively uncommon. Herein, we presented a 37-year-old man with maxillary sinus ACC metastasis to the right kidney eight years after surgical resection of the primary tumor. A successful right radical nephrectomy was performed followed by local radiotherapy and antineoplastic therapy. Unfortunately, the patient died of respiratory failure within eight months after the operation. To our knowledge, it is the first report of metastatic renal tumor from maxillary sinus ACC.