Adenoid cystic carcinoma of the external auditory canal with pulmonary metastasis: A case report and literature review

Adenoid cystic carcinoma (ACC) is a rare malignancy predominantly found in the salivary, lacrimal, upper gastrointestinal, and respiratory mucosal glands; adenoid cystic carcinoma of the external auditory canal (EAC) is particularly rare. Characterized by a proclivity for recurrence and metastasis, advanced adenoid cystic carcinoma often proves refractory to conventional chemotherapy. Novel therapeutic approaches, notably targeted therapies, are imperative to enhance treatment response rates in advanced adenoid cystic carcinoma patients. Herein, we present a case of primary adenoid cystic carcinoma affecting the right external auditory canal in a 56-year-old male presenting with symptoms of pruritus, swelling, pain, and hearing loss in the affected ear. Despite multiple attempts with diverse chemotherapy regimens yielding no success, the patient developed advanced lung metastases, prompting the utilization of anlotinib-targeted therapy. Subsequent administration of anlotinib led to a partial remission (PR), resulting in approximately 8 months of progression-free survival (PFS) in this individual.