A 12-year-old Asian girl presented with a 1-year history of a painless, slow-growing mass in the floor of her mouth. She was otherwise healthy and denied having dysphagia, odynophagia, weight changes, voice changes, fever, chills, nausea, vomiting, recent foreign travel, and tuberculosis contacts. The results of a recent purified protein derivative test were negative. Physical examination revealed no abnormalities except for a 3 × 4-cm nontender, firm, mobile mass that was palpable in the left anterolateral aspect of the floor of the mouth. Clear saliva was expressed from both submandibular ducts, and the submandibular gland was palpable as a separate entity. Tongue mobility was normal. Magnetic resonance imaging showed an enhancing, well-circumscribed soft tissue mass in the left submandibular space (Figure 1). The mass was subsequently excised in the operating room through an intraoral approach. Histopathologic examination demonstrated tumor cell nests separated by a thickened, hyalinized basement membrane (Figure 2). The cell nests were composed of 2 layers of cells: an inner layer of ductal epithelial cells that stained positive for keratin and an outer layer of cells with clear cytoplasm that stained positive for S100 protein, smooth muscle actin, and glial fibrillary acidic protein (Figure 3).