ABCDEs of melanoma

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].

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

Asymmetrical shape

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

Asymmetry of shape, structure and colour

Border irregularity

Colour variation

Diameter > 6 mm

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 in a melanocytic naevus in a white-skinned individual (but may be the usual colour for a dark-skinned person and can occur in seborrhoeic keratoses in all skin types).

Melanocytic naevus with fading border

Seborrhoeic keratosis with sharp border

Melanoma with mixed sharp and fading border

Colour variation

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

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

Diameter > 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 denote 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].

In contrast, the majority of melanocytic naevi are smaller than 6 mm in diameter throughout life.

Evolution

E is for Evolution (change). 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.

2012

2013

2017

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.

Pigmented basal cell carcinoma

Pigmented squamous cell carcinoma in situ

Pigmented actinic keratosis

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.

Seborrhoeic keratosis

Solar lentigo

Melanocytic naevus

Do all melanoma display ABCDE characteristics?

While the ABCDE criterion 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].

Nodular melanoma

Amelanotic melanoma

Small melanoma

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.

Elevated

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

Firm

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

Growing

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 weeks to months.

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