Seborrheic keratosis
Seborrheic keratosis is an extremely common benign epidermal growth of older adults that presents as a round or oval, sharply demarcated, waxy or verrucous plaque with a classic stuck-on appearance on the face, trunk, or upper extremities. Diagnosis is clinical based on the stuck-on morphology; no treatment is required, and irritated or cosmetically bothersome lesions can be removed by cryotherapy, curettage, or shave removal.
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What this article covers
- Overview
Definition: seborrheic keratosis is a very common, benign epidermal tumor of keratinocyte origin that arises during adulthood, most often in people older than 50 years.
- Epidemiology
Near-universal in older adults: seborrheic keratosis affects roughly 90% of adults over age 60.
- Risk factors
Advancing age: age is the dominant risk factor, with lesion number increasing steadily through the sixth, seventh, and eighth decades of life.
- Pathophysiology
Keratinocyte origin: seborrheic keratosis is a benign, pigmented neoplasm caused by squamous epithelial proliferation with keratin-filled cysts (horn cysts) visible within the lesion.
- Clinical features
Diagnostic pattern: round or oval, sharply demarcated papules or plaques with a waxy, warty, stuck-on appearance and a greasy or crumbly surface, often showing visible keratin plugs (horn cysts).
- Differential diagnosis
Solar lentigo: a flat, uniformly tan, stable macule, unlike the raised, waxy, stuck-on texture of a mature seborrheic keratosis.
- Diagnosis
Diagnostic basis: seborrheic keratosis is a clinical diagnosis made by visual inspection, based on the characteristic round or oval, sharply demarcated, waxy, stuck-on morphology; no laboratory testing is required for a typical lesion.
- Management
First step, for a typical asymptomatic lesion: no treatment or removal is needed; reassure the patient that the diagnosis is benign with no malignant potential.
- Complications
Irritation and excoriation: friction from clothing or scratching can cause inflammation, bleeding, or crusting of an otherwise asymptomatic lesion.
- Prognosis
Excellent, benign course: seborrheic keratosis has no malignant potential and does not require treatment for the vast majority of patients.
- Prevention
No proven primary prevention: because the cause of seborrheic keratosis is unknown and it is not linked to a modifiable exposure such as ultraviolet light, there is no established strategy to prevent new lesions from forming.
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