Dr. Shane Chapman, MD discusses Skin Cancer Squamous Cell Carcinoma Keratoacanthoma Variant. See more at www.dermnet.com PLEASE RATE AND COMMENT!!! Keratoacanthomas appear suddenly and grow rapidly. They reach a certain size, usually 0.5 cm to 2.0 cm, stop growing, and then regress weeks to months later. They begin as red-to-flesh colored, dome-shaped papules with a smooth surface and a central crater filled with a keratinous plug. The pathologist sometimes has difficulty differentiating a keratoacanthoma from SCC. While keratoacanthomas have been regarded in the past as self-limited, regressing lesions that resemble squamous cell carcinoma, most dermatologists today would classify them as squamous cell carcinoma variants. They should be treated as other forms of squamous cell carcinoma.