Submandibular Gland Adenoid Cystic Carcinoma

Ojas Shah and David L. Steward

History

A 52-year-old white woman is referred by her primary care physician for a persistent lump under the right jaw. The mass first appeared 6 weeks ago, and the patient was placed on Augmentin for a presumed diagnosis of acute sialadenitis. However, after 2 weeks of antibiotic therapy, the size of the jaw mass was undiminished, nor has it changed size in the last month. She denies any fevers, chills, night sweats, or other lumps in the neck. She also denies weight loss, persistent cough, dysphagia, odynophagia, hoarseness, difficulty chewing or moving her tongue, or weakness of the face. Her medical history is significant only for two spontaneous vaginal deliveries and arthroscopic knee surgery. She currently takes metoprolol for high blood pressure and prophylactic aspirin. She denies ever using tobacco and consumes two or three glasses of wine socially every week. On physical examination, her eyes, ears, oropharynx, hypopharynx, and larynx are unremarkable. The face is symmetric in appearance. The tongue is mobile and is unre-markable; the base of tongue and floor of mouth are soft. There is no purulent drainage from the Wharton duct, nor is a stone palpated in the duct. There is a right-sided 2 × 2 cm submandibular mass that is firm, nonmobile, and nontender. No other palpable neck masses or lymph nodes are found.

Differential Diagnosis—Key Points

1. The differential diagnosis can be generally classified into inflammatory and noninflammatory causes. Inflammatory causes include acute and chronic infectious lesions from bacterial (e.g., Staphylococcus, Streptococcus, Haemophilus, Escherichia coli, Bartonella, Mycobacterium, syphilis, Lyme disease), viral (e.g., Paramyxovirus, cytomegalobirus, Epstein-Barr virus, human immunodeficiency virus), and fungal (e.g., histoplasmosis, coccoid mycosis) agents, autoimmune diseases (Sjögren syndrome), and granulomatous diseases (Wegener, sarcoidosis). Noninflammatory causes include sialothiasis, sialocele, sialadenosis, benign or malignant neoplasms, radiation injury, or trauma.

3. About 50% of submandibular gland neoplasms are benign. The most common benign neoplasm of the parotid and submandibular glands is pleomorphic adenoma. Other benign neoplasms of the salivary glands include oncocytoma, Warthin tumor, and monomorphic adenoma. Malignant neoplasms include mucoepidermoid carcinoma, adenoid cystic carcinoma, acinic cell carcinoma, adenocarcinoma, carcinoma ex-pleomorphic adenoma, squamous cell carcinoma, and lymphoma. A neoplastic mass that is tender or associated with paralysis of the facial nerve (or its branches) or the hypoglossal nerve is suspicious for a malignancy. In malignant neoplasms, pain is usually indicative of perineural invasion, which predicts a worse prognosis than a neoplasm that is not painful.

Test Interpretation

1.