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.
History and exam
Key diagnostic factors
- lesions appear 'stuck-on
- localisation on torso or face
- yellow or light- to dark-brown-coloured lesions
- slightly raised, flat surface lesions
- wart-like texture
- multiple lesions
- itching (prurigo)
Other diagnostic factors
- round yellow-white horn pearls in the surface of lesions
- age over 50 years
- Fitzpatrick skin type I or II
- Fitzpatrick skin type IV, V or VI (dermatosis papulosa nigra)
- female sex (dermatosis papulosa nigra)
- family history
- sun/UV exposure
Investigations to consider
- biopsy and histopathological examination
- reflectance confocal microscopy (RCM)
irritated or itching lesions
raised seborrhoeic keratosis
flat seborrhoeic keratosis
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