Lichen Planus — ORE Part 1 MCQ
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Correct answer: D — Lichen planus
Lichen planus is a chronic mucocutaneous inflammatory disorder. The diagnosis is confirmed by: (1) bilateral symmetric white reticular striae (Wickham striae) on buccal mucosae—the classic oral presentation; (2) purplish, polygonal, pruritic papules on the wrists—the archetypal cutaneous presentation. Lichenoid drug reaction is excluded by the absence of medication history and the classic unifying pattern. Discoid lupus presents with different oral lesions (scaly erosive plaques, not reticular striae) and lacks the characteristic skin papules. Secondary syphilis causes non-pruritic maculopapules and oral mucous patches, not Wickham striae. Graft-versus-host disease requires prior stem cell transplantation and presents differently. The bilateral symmetry, reticular oral pattern, wrist-predominant pruritic papules, and mucocutaneous involvement make lichen planus the unifying diagnosis.
Reference: Warnakulasuriya, S. et al. (2020). 'Oral lichen planus'. In: Uptodate (peer-reviewed topic). PubMed/MEDLINE: https://pubmed.ncbi.nlm.nih.gov/32753462/. Also: 690-patient UK retrospective study of oral lichen planus confirming reticular pattern as most common intra-oral presentation with bilateral involvement in 95% (Thornhill, 2006; UCL Eastman): https://pubmed.ncbi.nlm.nih.gov/16910916/