Medical Encyclopaedia › Mole (short definition)
In brief: Moles, also called pigmented naevi (technically melanocytic naevi), are benign clusters of pigment-producing cells in the skin. Almost everyone has some. The vast majority remain harmless throughout life. It is important to notice changes, because melanoma rarely develops from a mole or can look similar to one.
How do moles develop?
Moles can be congenital or develop during life, especially in childhood and adolescence. How many form depends on hereditary predisposition, skin type and the amount of UV radiation, especially sunburn in childhood. In older age, some moles fade or disappear. In addition to ordinary moles, there are special forms such as congenital naevi, blue naevi or Spitz naevus in children. Other brown spots such as seborrhoeic warts or sun spots are not moles in the strict sense.
How can you recognise suspicious moles?
The ABCDE rule offers simple guidance:
- A – Asymmetry: irregular shape
- B – Border: blurred, ragged or jagged edges
- C – Colour: several shades, such as brown, black, red, grey or blue
- D – Diameter: larger than about five millimetres
- E – Evolution: changes in size, shape, colour or height
A mole that looks different from all the others (“ugly duckling”), itches, bleeds or weeps should also be examined by a dermatologist. The rule does not replace an examination: not every suspicious mole is malignant, and not every melanoma meets the criteria.
Who is at increased risk?
People with very many moles, several irregular (atypical or dysplastic) naevi, large congenital moles, fair, sun-sensitive skin, melanoma in the family or in their own history, and after frequent sunburn or sunbed use have an increased risk of melanoma. For them, regular dermatological check-ups at individually determined intervals are advisable.
Examination and skin cancer screening
During the examination, the dermatologist looks at the entire skin, including the scalp, soles of the feet and mucous membranes. With the dermatoscope, an illuminated magnifier, structures become visible that cannot be seen with the naked eye. With many moles, photographs can help to detect changes over time. In Germany, people with statutory health insurance are entitled to skin cancer screening every two years from the age of 35; some health insurers offer additional services. Between appointments, self-examination of the skin, if necessary with the help of a mirror or a trusted person, is advisable.
Removal
If malignancy is suspected, the mole is completely excised with a small safety margin and examined histologically. This is a short procedure under local anaesthesia. Medically justified removals are paid for by the health insurers. Moles that are to be removed for cosmetic reasons or because of constant irritation, for example at the waistband, are also usually excised or shaved off; purely cosmetic removals are paid for privately. Pigmented moles should not be lasered or frozen without a prior medical diagnosis, because tissue examination is then no longer possible.
Prevention
Consistent sun protection, especially for children, reduces the number of new moles and the risk of melanoma: avoid the midday sun, seek shade, wear clothing and a hat, use sunscreen in addition, avoid sunburn and do not use sunbeds.
Related terms in the encyclopaedia
Melanoma, Melanocytes, ABCDE rule, Dysplastic naevus, Congenital naevus, Spitz naevus, Dermatoscopy, Skin cancer screening, UV radiation
Sources
- Leitlinienprogramm Onkologie (AWMF, Deutsche Krebsgesellschaft, Deutsche Krebshilfe): S3-Leitlinie Diagnostik, Therapie und Nachsorge des Melanoms
- Leitlinienprogramm Onkologie: S3-Leitlinie Prävention von Hautkrebs
- Gemeinsamer Bundesausschuss (G-BA): Krebsfrüherkennungs-Richtlinie – Hautkrebs-Screening
- Deutsche Dermatologische Gesellschaft (DDG): Patienteninformationen zu Muttermalen und Hautkrebsvorsorge
Note: This article is for general information and does not replace advice, diagnosis or treatment from a doctor, dentist or pharmacist. Last updated: October 2026.