Floor of Mouth Carcinoma — ORE Part 1 MCQ

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HardOral MedicineFloor of Mouth CarcinomaORE Part 1

A 55-year-old man has a rapidly enlarging unilateral swelling in the floor of the mouth. On examination, it is firm, indurated and fixed to adjacent tissues. He reports new numbness of the ipsilateral lower lip. What is the most likely diagnosis?

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Correct answer: B — Floor-of-mouth squamous cell carcinoma

Explanation lettering: D = shown as A · A = shown as B · B = shown as C · C = shown as D

A is correct. A rapidly enlarging, indurated and fixed oral soft-tissue mass is suspicious for invasive malignancy; associated sensory change is an additional red-flag feature. In this location, oral squamous cell carcinoma is the most likely diagnosis. UK NHS sources identify a persistent oral lump or swelling and oral numbness as possible features of mouth cancer. A ranula is usually a fluctuant, cystic swelling rather than a fixed indurated mass. Submandibular sialadenitis would more often cause painful gland swelling, often meal-related or associated with infection. A submandibular gland neoplasm is possible but is anatomically less consistent with a primary floor-of-mouth lesion. An odontogenic abscess should have a dental source and acute inflammatory features rather than progressive fixation with paraesthesia.

Reference: NHS England. NHS partners with Asda to put crucial mouth cancer symptoms on toothpaste and mouthwash. 2024. https://www.england.nhs.uk/2024/07/nhs-partners-with-asda-to-put-crucial-mouth-cancer-symptoms-on-toothpaste-and-mouthwash/