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Keratoacanthoma
is a round, firm, usually flesh-colored nodule, with sharply sloping
borders and a characteristic central crater containing keratinous
material, which usually resolves spontaneously.
Etiology is unknown. Most consider these lesions to be well-differentiated squamous cell carcinomas with a tendency to involute.
Development is rapid; usually the lesion reaches its full size, which may be > 5 cm, within 1 or 2 mo. Common sites are sun-exposed areas, the face, the forearm, and the dorsum of the hand. Spontaneous involution may start within a few months. However, because this lesion cannot be relied upon to involute, biopsy or excision is recommended. Spontaneous involution may leave substantial scarring; surgery or intralesional injections with 5- fluorouracil or corticosteroids usually yield better cosmetic results, and excision allows histologic confirmation of the diagnosis. Some untreated lesions metastasize.
Last full review/revision November 2005
Content last modified November 2005
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