Numb Chin Syndrome Malignancy — ORE Part 1 MCQ

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HardOral MedicineNumb Chin Syndrome MalignancyORE Part 1

A 55-year-old woman reports progressive numbness of the right lower lip and chin for 6 weeks. She has had no recent dental treatment, local anaesthetic injection or facial trauma. There is no dental pain, swelling or clinical evidence of odontogenic infection. What is the most important diagnosis to consider?

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Correct answer: E — Malignancy involving the mental or inferior alveolar nerve

This is numb chin syndrome: unilateral hypoesthesia in the mental/inferior alveolar nerve distribution. In an adult with a progressive course and no dental, traumatic or injection-related explanation, malignant infiltration or compression of the nerve must be excluded urgently; it may reflect mandibular metastasis, a local tumour or more proximal malignant involvement. Bell's palsy produces facial motor weakness rather than isolated lower-lip sensory loss. Trigeminal neuralgia causes brief, paroxysmal electric-shock pain, not persistent progressive numbness. Multiple sclerosis can cause sensory symptoms but is not the key diagnosis indicated by this focal mental-nerve presentation. Odontogenic infection can cause altered sensation but would usually have supporting local symptoms or signs, which are specifically absent.

Reference: Perez C, de Leeuw R, Escala P F, Fuentealba R, Klasser GD. Numb chin syndrome: What all oral health care professionals should know. Journal of the American Dental Association. 2023;154(1):79-93. https://pubmed.ncbi.nlm.nih.gov/29680775/