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Keratoacanthoma — MFDS Part 1 MCQ

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ModerateOral PathologyKeratoacanthomaMFDS Part 1

A 72-year-old man presents with a dome-shaped, crateriform lesion containing a central keratin plug on the sun-exposed lower lip. The clinical differential diagnosis includes keratoacanthoma and squamous cell carcinoma. Which natural-history pattern is most characteristic of keratoacanthoma?

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Correct answer: B — Rapid enlargement over weeks, with possible spontaneous regression

Keratoacanthoma characteristically has a rapid proliferative phase over several weeks and may subsequently regress spontaneously. It commonly presents on sun-exposed skin as a symmetrical dome-shaped or crateriform lesion with a central keratin plug. Slow infiltrative growth, early nodal metastasis and progressive pigmentation are not characteristic natural-history patterns. Recurrent multifocal lesions can occur in uncommon keratoacanthoma syndromes but are not typical of a solitary lesion. Importantly, spontaneous regression should not justify observation: keratoacanthoma may be clinically and histologically difficult to distinguish from well-differentiated squamous cell carcinoma, so complete excision is generally recommended.

Reference: Tisack A, et al. A clinical and biological review of keratoacanthoma. British Journal of Dermatology. 2021;185(3):487–498. https://pubmed.ncbi.nlm.nih.gov/33864244/