Keratoacanthoma Lip — ORE Part 1 MCQ
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Correct answer: A — Keratoacanthoma
**Answer: A. Keratoacanthoma** The clinical presentation is characteristic of keratoacanthoma: a painless, dome-shaped papule with a central keratin plug on sun-exposed lip skin, exhibiting rapid growth over 3 weeks. Keratoacanthoma is a benign epithelial tumour originating from the hair follicle that presents classically with these features and spontaneously regresses over weeks to months. Why distractors fail: - **B. Squamous cell carcinoma**: Although histopathological overlap is significant and lip SCC must be excluded by biopsy, SCC typically lacks a prominent central keratin plug and presents with different growth kinetics and ulceration patterns. - **C. Basal cell carcinoma**: Common on the lip but characteristically presents as a pearly nodule with telangiectasia and ulceration; a prominent keratin plug is not typical. - **D. Verruca vulgaris**: Usually smaller, multiple, and lacks the crateriform architecture and substantial central keratin plug. - **E. Molluscum contagiosum**: Presents as multiple small lesions, typically in younger patients; the central umbilication differs from a true keratin plug. Clinically, this 3-week growth with characteristic morphology points to keratoacanthoma. In UK practice, such lesions warrant biopsy to confirm diagnosis and exclude SCC.
Reference: Systematic review: Clinicopathological analysis of oral and perioral keratoacanthoma, PubMed Central PMC12742887 (2024); UK NHS referral guidance: Devon Formulary—Skin 2-week wait pathway; Peer-reviewed literature: Keratoacanthoma presentation and SCC differential diagnosis (PubMed 2023–2025). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12346027/