DermatologicalICD-10: L82.1Extremely common; most adults over 50 have at least one, and many have multiple

Seborrheic Keratosis

Also known as: Seborrhoeic wart, Senile wart, Basal cell papilloma

A seborrheic keratosis is a common, harmless skin growth that appears as a waxy, slightly raised, 'stuck-on' patch, ranging from light tan to dark brown or black. They usually start to appear in middle age and become more numerous with time; most people over 50 have at least one and many have dozens. They can occur anywhere except the palms and soles, most often on the chest, back, scalp, face, and neck. Although they can look alarming, particularly when dark, seborrheic keratoses are not cancerous, not contagious, and not caused by sun damage or any virus. They need no treatment unless they become irritated, catch on clothing, or are cosmetically bothersome. The main reason to have one checked is to be sure it is not a melanoma, which can occasionally look similar.

At a Glance

Common symptoms
A round or oval raised growth with a waxy, scaly, or slightly warty surface, A 'pasted-on' appearance, as if it could be peeled off the skin, Colour ranging from white or tan to brown or black, often with a uniform tone
Main treatments
No treatment is needed for typical seborrheic keratoses, Cryotherapy (freezing with liquid nitrogen) for lesions that are irritated or bothersome, Shave removal or curettage under local anaesthetic, with the sample sent for examination
Category
Dermatological · Extremely common; most adults over 50 have at least one, and many have multiple
See a doctor if
A growth that is changing in size, shape, or colour, has an irregular border, or shows several colours

Symptoms

A round or oval raised growth with a waxy, scaly, or slightly warty surface
A 'pasted-on' appearance, as if it could be peeled off the skin
Colour ranging from white or tan to brown or black, often with a uniform tone
Size from a few millimetres to several centimetres
Multiple growths, commonly on the trunk, face, scalp, or neck
Occasional itching, irritation, or bleeding if rubbed or caught on clothing

Causes

  • The exact cause is unknown; it involves a benign overgrowth of cells in the outer layer of the skin
  • Genetics: a tendency to develop many seborrheic keratoses often runs in families
  • Ageing, which is the strongest association
  • Possibly friction in skin folds, where they are common
  • Not caused by a virus, sun exposure, or poor hygiene

Risk Factors

  • Age over 40, with numbers increasing each decade
  • Family history of multiple seborrheic keratoses
  • Pregnancy or hormone treatment, which can trigger growth in some people
  • All skin types are affected; small dark variants are particularly common on the faces of people with darker skin

Diagnosis

  • Visual examination, often with a dermatoscope, which usually shows a characteristic pattern
  • Skin biopsy if the growth looks unusual, is changing, or cannot be confidently distinguished from melanoma or other skin cancers
  • A full skin check, particularly if there are many lesions or any has changed

Treatment

  • No treatment is needed for typical seborrheic keratoses
  • Cryotherapy (freezing with liquid nitrogen) for lesions that are irritated or bothersome
  • Shave removal or curettage under local anaesthetic, with the sample sent for examination
  • Electrocautery or laser removal for cosmetic reasons
  • Topical treatments such as hydrogen peroxide 40% solution, available in some countries, for selected lesions
  • Supportive: avoiding scratching or picking, and protecting lesions that rub on clothing or jewellery with a soft dressing

Prevention

  • There is no known way to prevent seborrheic keratoses
  • Become familiar with your own growths so you can spot changes
  • Avoid rubbing or irritating existing lesions
  • Have any new, changing, or unusual growth checked rather than assuming it is harmless

When to See a Doctor

  • A growth that is changing in size, shape, or colour, has an irregular border, or shows several colours
  • A lesion that bleeds, becomes sore, or does not heal
  • A sudden crop of many new growths over weeks, which rarely can signal an internal condition
  • A growth you cannot confidently identify; a doctor can distinguish seborrheic keratosis from melanoma
  • Lesions that are painful, itchy, or catching on clothing and you would like removed

Frequently Asked Questions

Related Conditions

Actinic Keratosis

Dermatological

Skin Cancer

Cancer

Melanoma

Cancer

Warts

Dermatological

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