Floor of Mouth SCC Bone Invasion — ORE Part 1 MCQ

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HardOral MedicineFloor of Mouth SCC Bone InvasionORE Part 1

A 60-year-old patient has a painless, firm, fixed swelling in the floor of the mouth and ipsilateral submandibular lymphadenopathy. Contrast-enhanced CT demonstrates a soft-tissue mass with erosion of the adjacent lingual mandibular cortex. Which diagnosis is most likely?

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

The diagnosis is **floor-of-mouth squamous cell carcinoma**. Oral cavity cancer includes the floor of mouth, and squamous cell carcinoma is its predominant histological type. A firm fixed lesion, ipsilateral cervical nodal enlargement and an enhancing soft-tissue mass with adjacent cortical mandibular erosion together indicate locally invasive malignancy. CT is particularly useful for demonstrating cortical mandibular involvement in floor-of-mouth SCC. A plunging ranula and dermoid cyst are usually fluctuant cystic swellings and do not cause regional nodal disease or cortical destruction. Ludwig angina is an acute, painful, spreading cellulitis with systemic illness rather than a discrete fixed mass. Submandibular sialolithiasis typically causes intermittent meal-related salivary pain and swelling, sometimes with a visible calculus, not an invasive mass with nodal enlargement.

Reference: NICE, Improving Outcomes in Head and Neck Cancers: The Manual, section on oral cavity cancer, 2004; https://www.nice.org.uk/guidance/CSG6/documents/head-and-neck-cancers-first-consultation-full-guideline2. Supporting imaging evidence: Curtin HD. CT and MR imaging of squamous cell carcinoma of the tongue and floor of the mouth, Radiographics, 1996; https://pubmed.ncbi.nlm.nih.gov/8835972/