Seborrhoeic keratosis

Seborrhoeic keratosis are common, multiple, benign tumours 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.

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 and displeasing, can be initially treated with cryotherapy and curettage.

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

Seborrhoeic keratosis is a common, benign skin tumour most commonly found on the torso and forehead. The lesions clinically appear in multiples as well-circumscribed grey-brown-to-black plaques with a 'stuck-on' appearance. Later the plaques can become raised and may show a verrucous surface. Most lesions do not exceed 1 cm in diameter. The lesions are normally painless and require no treatment.[1]Pierson D, Bandel C, Ehrig T, et al. Benign epidermal tumors and proliferations. In: Bolognia JL, Jorizzo JL, Rapini RP, eds. Dermatology. London: Mosby; 2003:597-602.[2]MacKie RM, Quinn AG. Non-melanoma skin cancer and other epidermal skin tumors. In: Burns T, Breathnach SM, Cox N, et al, eds. Rook's textbook of dermatology. 7th ed. Oxford, UK: Blackwell; 2004:36-45.[3]Weedon D. Chapter 31: Tumors of the epidermis. In: Weedon D. Skin pathology. 2nd ed. London: Churchill Livingstone; 2002:765-771.[4]Altmeyer P, Bacharach-Buhles M, eds. Enzyklopadie dermatologie, allergologie, umweltmedizin. Berlin: Springer; 2002.[5]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]: Seborrhoeic 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]: Seborrhoeic 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]: Seborrhoeic 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 seborrhoeic 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 seborrhoeic 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 seborrhoeic 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 seborrhoeic 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 seborrhoeic 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].