What Causes Keratoacanthoma?

Repeated ultraviolet exposure can damage skin cells over time. Against that background, a keratoacanthoma may appear as a firm, dome-shaped bump with a central plug of keratin. It often changes noticeably over a short period and may occur on sun-exposed areas such as the face, ears, backs of the hands, or forearms. Its appearance can overlap with squamous cell skin cancer, so visual inspection alone may not settle the diagnosis. Sun-damaged skin is therefore a useful clue, not a reason to watch a new lump without advice.

Arrange a prompt examination for a new, fast-growing, crusted, or firm bump. Do not squeeze, shave, or repeatedly pick it, since that can cause bleeding and make assessment harder. Use shade, protective clothing, and broad-spectrum sunscreen on exposed skin while arranging care. A clinician may examine the lesion and recommend sampling or removal so the tissue can be identified accurately. The plan depends on its size, site, growth pattern, and the surrounding skin.

Seek prompt care if a lump grows quickly, bleeds, becomes painful, forms a persistent crust, or does not heal. Same-day advice is sensible for heavy bleeding, spreading redness, fever, or severe pain. Do not wait for a central plug to fall out before seeking an assessment.

Ask whether the lesion needs a biopsy or complete removal, how soon it should be assessed, and which features make keratoacanthoma or another skin cancer more likely. Ask how to protect nearby sun-damaged skin during healing.