Adenoid Cystic Carcinoma of the Base of the Tongue

A BSTRACT Adenoid cystic carcinoma (ACC) is a rare malignant salivary gland tumor, accounting for approximately 1% of all head-and-neck malignancies. While ACC most commonly arises in the major and minor salivary glands, involvement of the base of the tongue is exceptionally rare, resulting in a diagnostic and therapeutic challenge. We present a case of a 42-year-old male who presented with a 20-day history of an intraoral swelling and dysphagia. Clinical examination showed a smooth cystic mass at the base of the tongue. Positron emission tomography–computed tomography imaging demonstrated a 41 mm × 43 mm × 46 mm metabolically active lesion involving the base of the tongue, floor of the mouth, and preepiglottic space, with bilateral cervical lymphadenopathy. Histopathological examination confirmed ACC with a predominantly cribriform pattern (85%), perineural invasion, and no lymphovascular involvement. Surgery was offered but declined by the patient. The patient subsequently underwent concurrent chemoradiotherapy and achieved a complete metabolic response at 2 months posttreatment. Surveillance imaging at 11 months confirmed complete remission, persisting even at 18-month follow-up. This case highlights that ACC of the base of the tongue, although rare, can achieve complete metabolic response with concurrent chemoradiotherapy even in the absence of surgical intervention. Early recognition, appropriate imaging, and multidisciplinary management are crucial for optimal patient outcomes.