Adenoid cystic carcinoma of the floor of the mouth: A case report

Abstract

Adenoid cystic carcinoma (ACC) is a rare malignant tumor primarily affecting the salivary glands, most commonly arising in the minor salivary glands of the hard palate. Its occurrence in less common sites such as the floor of the mouth is rare, representing a small percentage of intraoral minor salivary gland tumors. ACC is characterized by slow growth but aggressive biological behavior, including a high risk of perineural invasion, local recurrence, and late distant metastases, which complicate long-term prognosis. The mainstay of treatment is radical surgical excision with clear margins, usually followed by postoperative radiotherapy, while chemotherapy shows limited effectiveness.This is a case presentation of a 55-year-old woman with a painless, slowly enlarging mass on the floor of the mouth, present for two years. Imaging and clinical findings indicated a well-defined lesion confined to the right hemilingual region without nodal involvement. Complete surgical excision was performed, and histopathology confirmed cribriform subtype ACC with negative margins and no perineural invasion. Adjuvant radiotherapy was administered due to the tumor’s location and known risk for recurrence. At six months follow-up, the patient remains disease-free. This case underscores the diagnostic challenge of ACC in uncommon intraoral sites and highlights the importance of a multidisciplinary approach, complete resection, and vigilant long-term surveillance.