Pleomorphic adenoma of parotid gland — ORE Part 1 MCQ

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HardOral Medicine and Oral PathologyPleomorphic adenoma of parotid glandORE Part 1

A 47-year-old woman has a slow-growing, painless, firm swelling anterior to the ear for two years. Facial nerve function is normal, the overlying skin is mobile, and ultrasound shows a well-circumscribed superficial parotid mass. There is no fever. What is the most likely diagnosis?

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Correct answer: A — Pleomorphic adenoma

The answer is A. Pleomorphic adenoma. The cardinal clinical features—slow 2-year growth, painless presentation, firm consistency, well-circumscribed border, normal facial nerve function, and mobile overlying skin—are hallmark of a benign parotid tumour, and pleomorphic adenoma is the most common (65% of all parotid tumours). Age 47 fits the benign profile (4–5th decade) better than malignancy (>6th decade). The UK Multidisciplinary Guidelines specify that discrete, well-defined, mobile lumps are consistent with benign disease, whereas pain, rapid growth, fixity, and nerve involvement suggest malignancy. Option C (mucoepidermoid carcinoma, a common malignancy) lacks any features of malignancy in this case. Option B (acute bacterial parotitis) would present acutely with fever and pain, not as a 2-year asymptomatic mass. Option E (mumps) is acute viral parotitis with systemic features. Option D (submandibular sialolithiasis) occurs in the submandibular duct, not the parotid, and presents with acute pain related to meals.

Reference: Management of Salivary Gland Tumours: United Kingdom National Multidisciplinary Guidelines, 2016, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4873929/