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ABCDEs of melanoma

Author: Qiuyu Jin, Medical Student, University of Auckland, Auckland, New Zealand. DermNet NZ Editor in Chief: Adjunct A/Prof Amanda Oakley, Dermatologist, Hamilton, New Zealand. Copy edited by Gus Mitchell/Maria McGivern. June 2019.

ABCDEs of melanoma — codes and concepts

What are the 'ABCDEs' of melanoma?

The 'ABCDEs' of melanoma refers to an acronym designed to help the public and clinicians identify features in a skin lesion that may suggest a flat or in-situ melanoma (superficial spreading melanoma, lentigo maligna melanoma, or acral lentiginous melanoma) [1]. The acronym is:

Border irregularity
Colour variation
Diameter larger than 6 mm
Evolving or changing.

An additional letter 'F' which stands for ‘funny looking’ or ‘feels funny’, may also help in identifying a possible melanoma [2].


A is for Asymmetry. A melanocytic naevus (harmless mole) is usually symmetrical, whereas melanoma is often irregular or asymmetrical in shape.

Melanoma ABC signs

Border irregularity

B is for Border irregularity. A melanocytic naevus has smooth and even borders, whereas a melanoma often has irregular and hard-to-define borders.

On careful inspection, the pigmented component of a flat melanocytic naevus fades out towards the edge, whereas the edges of a solar lentigo or a seborrhoeic keratosis are well defined. The edges of a melanoma tend to have both well-defined and fading segments.

B is also used for 'black', which is an uncommon colour for a melanocytic naevus in a white-skinned individual, but may be the usual colour for a dark-skinned person. The colour black can occur in seborrhoeic keratoses in all skin types.

Borders of pigmented skin lesions

Colour variation

C is for Colour variation. A melanocytic naevus usually has a single shade of colour or two shades of colour with one occurring inside the other or regularly repeated (generally pink, brown, or tan).

Variation in colour of melanocytic naevi

Melanoma can be brown but can have as many as five or six colours (blue, black, brown, tan, grey, pink, and red). These colours are unevenly or irregularly distributed.

Variation in colour of melanoma

Diameter larger than 6 mm

D is for Diameter. Most melanomas are greater than 6 mm in diameter when they are diagnosed (this is about the size of a pencil eraser).

D is sometimes used to mean 'dark colour'.

D is also used for 'different’. Benign moles resemble each other, whereas a melanoma appears unique and very different from the patient’s other lesions.

A mole that is obviously different from the others is sometimes called an ugly duckling and must be considered suspicious even if it does not fulfil the ABCDE criteria [3,4].

Melanomas larger than 6 mm in diameter at diagnosis
Melanocytic naevi smaller than 6 mm in diameter

Evolving or changing

E is for Evolving or changing. A melanocytic naevus is usually stable and does not change in size, shape, or colour, whereas a melanoma changes over time. Change in size, colour, shape, or structure may be noted over months to years.

An evolving melanoma

What other skin lesions might have ABCDEs?

The ABCDE criteria are not very specific for melanoma, as some or all of the criteria may be displayed by another skin cancer, such as a pigmented basal cell carcinoma or pigmented squamous cell carcinoma.

Malignant melanoma mimics

A benign lesion can be asymmetrical in shape, have an irregular border, colour variation, and be larger than 6 mm in diameter. Examples include congenital melanocytic naevus, acquired melanocytic naevus, solar lentigo, or seborrhoeic keratosis.

Melanocytic naevi can also evolve in some circumstances (such as darkening after exposure to the sun, and becoming more elevated with age); seborrhoeic keratoses and solar lentigines routinely evolve over time.

Clinicians trained in dermoscopy can often correctly diagnose skin lesions, but sometimes a biopsy will be needed to confirm a diagnosis.

Benign melanoma mimics

Do all melanoma display ABCDE characteristics?

While the ABCDE criteria has been proven to be very helpful in identifying a potential melanoma, it cannot be used to reliably recognise all melanomas. A melanoma may be symmetrical in shape, with a uniform border, without much colour variation, and it can be diagnosed when it is smaller than 6 mm in diameter.

The ABCDE criteria are particularly unhelpful in the diagnosis of some less common subtypes of melanomas such as nodular melanoma, desmoplastic melanoma, and melanoma in childhood, as these often lack the ABCDE features [5–8].

Melanomas without ABCDs

The 'EFGs' of melanoma

Nodular melanoma is more likely to metastasise and result in the patient’s death than a flat melanoma.

The EFGs of melanoma refer to an acronym designed to help the public and clinicians identify skin changes in a pigmented lesion typical of nodular melanoma. This acronym being:



E is for Elevated. Benign lesions can be elevated (eg, a dermal naevus, dermatofibroma, or cyst), but a new elevated or thickened lesion may be suspicious for nodular melanoma or another form of skin cancer.


F is for Firm. Benign lesions can feel firm (especially dermatofibroma), but this is also a feature of nodular melanoma.


Benign skin lesions tend to remain stable or change slowly over years to decades. They can also rapidly change in appearance over hours to days if injured, inflamed, bleeding, or affected by eczema (eg, Meyerson naevus).

Nodular melanoma tends to grow rapidly with changes noted over days to months.

Nodular melanoma with EFG characteristics

Why are these ABCDEs and EFGs important?

Melanoma is a serious form of skin cancer and can progress quickly. It is treatable if caught early but if it is left untreated for long enough, it may spread to other parts of the body (metastatic melanoma) and this can be life-threatening.

Knowing the ABCDEs and EFGs of melanoma can help you look for early signs of melanoma when performing a regular self-skin examination.

See our video on how to perform a self-skin examination.

I have a skin lesion I am concerned about, what should I do?

If you have a skin lesion with ABCDE or EFG characteristics that concerns you, see your doctor as soon as possible for assessment. You may be referred to a specialist for another opinion and surgery.

See smartphone apps to check your skin.
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Related information



  1. Melanoma Research Foundation. The ABCDEs of melanoma. Available at: (accessed 28 May 2019).
  2. Jensen JD, Elewski BE. The ABCDEF rule: Combining the “ABCDE Rule” and the “ugly duckling sign” in an effort to improve patient self-screening examinations. J Clinical Aesthet Dermatol 2015; 8: 15. PubMed Central
  3. Gachon J, Beaulieu P, Sei JF, et al. First prospective study of the recognition process of melanoma in dermatological practice. Arch Dermatol 2005; 141: 434–8. PubMed
  4. Grobb JJ, Bonerandi JJ. The 'ugly duckling' sign: identification of the common characteristics of nevi in an individual as a basis for melanoma screening. Arch Dermatol 1998; 134: 103–4. DOI: 10.1001/archderm.134.1.103-a. PubMed
  5. Whited JD, Grichnik JM. The rational clinical examination. Does this patient have a mole or a melanoma? JAMA 1998; 279: 696–701. DOI: 10.1001/jama.279.9.696. PubMed
  6. Harrington E, Clyne B, Wesseling N, et al. Diagnosing malignant melanoma in ambulatory care: a systematic review of clinical prediction rules. BMJ Open 2017; 7: e014096. DOI: 10.1136/bmjopen-2016-014096. PubMed
  7. Hawryluk EB, Pappo AS, Marghoob AA, Bahrami A. Melanoma in children. UpToDate. Updated May 2018. Available at: (accessed 28 May 2019).
  8. Chamberlain AJ, Fritschi L, Kelly JW. Nodular melanoma: patients' perceptions of presenting features and implications for earlier detection. J Am Acad Dermatol 2003; 48: 694–701. DOI: 10.1067/mjd.2003.216. PubMed

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