Seborrheic keratosis

Seborrheic keratoses are common, multiple, benign tumors of the skin.

They usually appear in the fourth and fifth decades of life and their prevalence increases with age and sun exposure.

They appear as well-circumscribed "stuck-on" plaques or papules and may look like warts.

Most important differential diagnosis, and of patient concern, is malignant melanoma.

They are usually asymptomatic but can become irritated and inflamed spontaneously or because of friction from clothing.

Treatment is not necessary because of their benign nature, but if irritated, itching or cosmetically unacceptable to the patient, they can be initially treated with cryotherapy or curettage.

Seborrheic keratosis is a common, benign skin tumor most commonly found on the torso and forehead. The lesions classically appear in multiples as well-circumscribed plaques with a "stuck-on" appearance. Later the plaques can become raised and may show a verrucous surface. Lesions can display a variety of colors, but are usually yellow or light-to-dark brown. Most lesions do not exceed 1 cm in diameter. The lesions are normally painless and require no treatment.​​​​[1]Seaton E, Madan V. Benign keratinocytic acanthomas and proliferations. In: Barker J, Griffiths C, Bleiker T, eds. Rook's textbook of dermatology. 10th ed. Hoboken, NJ: John Wiley & Sons, Ltd; 2024.[2]Patterson JW. Chapter 32: Tumors of the epidermis. In: Patterson JW. Weedon's skin pathology. 6th ed. Philadelphia, PA: Elsevier; 2025: 877-936.​​​​​​[3]Yeatman JM, Kilkenny M, Marks R. The prevalence of seborrhoeic keratoses in an Australian population: does exposure to sunlight play a part in their frequency? Br J Dermatol. 1997;137:411-414. http://www.ncbi.nlm.nih.gov/pubmed/9349339?tool=bestpractice.com [Figure caption and citation for the preceding image starts]: Seborrheic keratosis on the chest of an elderly womanFrom the collection of Dr Braun and Dr Kolm, used with permission [Citation ends].[Figure caption and citation for the preceding image starts]: Seborrheic keratosis of the chest: clinical overview imageFrom the collection of Dr Braun and Dr Kolm, used with permission [Citation ends].[Figure caption and citation for the preceding image starts]: Seborrheic keratosis of the chest: clinical close-up imageFrom the collection of Dr Braun and Dr Kolm, used with permission [Citation ends].[Figure caption and citation for the preceding image starts]: Dermoscopic image of seborrheic keratosis on the chestFrom the collection of Dr Braun and Dr Kolm, used with permission [Citation ends].[Figure caption and citation for the preceding image starts]: Clinical close-up image of seborrheic keratosis on the back of a 40-year-old manFrom the collection of Dr Braun and Dr Kolm, used with permission [Citation ends].[Figure caption and citation for the preceding image starts]: Clinical overview image of seborrheic keratosis on the back of a 40-year-old manFrom the collection of Dr Braun and Dr Kolm, used with permission [Citation ends].[Figure caption and citation for the preceding image starts]: Clinical image of an example of a dark-brown pigmented seborrheic keratosisFrom the collection of Dr Braun and Dr Kolm, used with permission [Citation ends].[Figure caption and citation for the preceding image starts]: Example of a dark-brown pigmented seborrheic keratosis. Dermoscopic image: see yellowish horn pearls and dark brown holes corresponding to so-called "pseudo-follicular openings"From the collection of Dr Braun and Dr Kolm, used with permission [Citation ends].