Keratoacanthoma Clinical Presentation

Updated: Feb 24, 2020
  • Author: Tsu-Yi Chuang, MD, MPH, FAAD; Chief Editor: William D James, MD  more...
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Keratoacanthoma (KA) typically grows rapidly, attaining 1-2 cm within weeks, followed by a slow involution period lasting up to 1 year and leaving a residual scar if not excised preemptively. Since expedient therapy almost always is instituted, the true natural course of the tumor cannot be confirmed with certainty.


Physical Examination

Pertinent physical findings in keratoacanthoma (KA) are limited to the skin. Lesions typically are solitary and begin as firm, roundish, skin-colored or reddish papules that rapidly progress to dome-shaped nodules with a smooth shiny surface and a central crateriform ulceration or keratin plug that may project like a horn. Most keratoacanthomas occur on sun-exposed areas. The face, neck, and dorsum of the upper extremities are common sites. Truncal lesions are rare. Lesions usually are skin-colored to pinkish-red. Unaffected skin retains its normal appearance. Note the images below.

Keratoacanthoma (squamous cell carcinoma-keratoaca Keratoacanthoma (squamous cell carcinoma-keratoacanthoma or SCC-KA type) on inner canthus.
Keratoacanthoma of the left forehead. Keratoacanthoma of the left forehead.
Close-up view of the keratoacanthoma. Close-up view of the keratoacanthoma.
Keratoacanthoma lesion (squamous cell carcinoma-ke Keratoacanthoma lesion (squamous cell carcinoma-keratoacanthoma or SCC-KA type).