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Keratoacanthoma: Epidemiology, risk factors, and diagnosis

Jerry D Brewer, MD
Section Editor
June K Robinson, MD
Deputy Editor
Rosamaria Corona, MD, DSc


Keratoacanthoma (KA) is a cutaneous tumor that most commonly presents as a dome-shaped nodule with a central keratin-filled crater (picture 1A-E) [1]. KA most frequently develops on hair-bearing, sun-exposed skin. Middle-aged and elderly adults with fair complexions are most frequently affected [2].

A distinguishing feature of KA is a clinical course characterized by rapid initial growth followed by a variable period of lesion stability and subsequent spontaneous resolution [2]. The recognition of this unique characteristic in a tumor with clinical and histopathologic features that closely resemble cutaneous squamous cell carcinoma has led to significant debate over the classification of this lesion.

The epidemiology, risk factors, and diagnosis of KA will be discussed here. The management and prognosis of KA is reviewed separately. (See "Keratoacanthoma: Management and prognosis".)


Although KA is a common tumor, the potential for spontaneous resolution, the variability in documentation of lesions as KA or squamous cell carcinoma, and the relative paucity of epidemiological studies performed on this disease hinder definitive conclusions on tumor incidence. The vast majority of reported cases of KA have occurred in fair-skinned individuals [3]. (See 'Risk factors' below.)

KA can occur at any age, and may present as a solitary lesion (the most common presentation) or infrequently in the context of specific disorders associated with multiple KAs [4-7] (see 'Multiple keratoacanthomas' below). Solitary KA has a peak incidence between the ages of 50 and 69 [2]; rarely, lesions develop in individuals under the age of 20 [4]. Data on the distribution of KA among the sexes vary. Estimates of the sex ratio range from a similar incidence in both sexes to a three times greater risk for KA among males [3,8,9].

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Literature review current through: Dec 2017. | This topic last updated: Sep 20, 2016.
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