Keratoacanthomas (KA) are usually asymptomatic and develop rapidly over 2 to 6 weeks. The rapid enlargement of a dome-shaped nodule of up to 1 cm in diameter with a central keratin-filled plug is typical (Fig. 35-1). KA usually appear on sun-exposed areas of the face, neck, arms, and hands. Rare syndromes exist in which multiple KA develop. The Ferguson–Smith type of KA consists of multiple, large KA; the Gryzbowski type consists of multiple, eruptive small lesions.