Lichenoid Drug Reaction — ORE Part 1 MCQ

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ModerateOral MedicineLichenoid Drug ReactionORE Part 1

A 50-year-old woman presents with a painful, white, reticular lesion on her left buccal mucosa that appeared 2 weeks after starting enalapril for hypertension. She has no history of oral lichen planus. What is the most likely diagnosis?

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Correct answer: B — Lichenoid drug reaction

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

The most likely diagnosis is A: Lichenoid drug reaction. Three features are decisive: (1) Temporal causality – lesion onset 2 weeks after starting enalapril, an ACE inhibitor known to cause oral lichenoid reactions; (2) Clinical morphology – white reticular appearance with pain, typical of drug-induced lichenoid lesions; (3) Negative history – absence of prior oral lichen planus excludes idiopathic OLP, which presents as a chronic autoimmune disorder rather than an acute drug-induced reaction. Oral lichenoid drug reactions represent a T-cell mediated mucosal response to systemic medication and typically resolve upon drug discontinuation. Distractor B (OLP) is excluded by explicit negative history and acute temporal relationship. Distractors C–E lack the characteristic reticular white morphology, temporal relationship to medication, or pain profile expected in this clinical scenario.

Reference: Oral lichenoid drug reaction associated with antihypertensive and hypoglycemic drugs. Published 2010. https://pubmed.ncbi.nlm.nih.gov/20120430/; Angiotensin-converting enzyme inhibitors implicated in oral mucosal lichenoid reactions. Published 1991. https://pubmed.ncbi.nlm.nih.gov/2536146/