ABCDEFG of Melanoma

The "ABCDE" of melanoma is an acronym that has been developed to help clinicians and the public identify features in a skin lesion that may suggest an early or in situ melanoma.

'A' stands for Asymmetry

'B' stands for Border irregularity

'C' stands for Colour variability/Change

'D' stands for Different

'E' stands for Evolving

The "EFG" of melanoma is another acronym that has been designed to help clinicians and the public identify skin changes in a lesion that may suggest a nodular melanoma. In this context, nodular refers to skin lesions that appear as bumps greater than 1 cm in diameter.

'E' stands for Elevated

'F' stands for Firm

'G' stands for Growing

Each acronym is examined in greater detail below.

A - Asymmetry

A melanocytic naevus is usually symmetrical, while melanoma usually appears in an irregular or asymmetrical shape and/or colour.

B - Border Irregularity

A melanocytic naevus has even, smooth borders, while melanoma has irregular, blurry, or pointed edges and a hard-to-define border. During careful skin examination, the pigmented components of a healthy-looking melanocytic naevus fade out towards the edge, while edges of seborrhoeic keratosis or a solar lentigo are well defined. Similarly, the edges of melanoma have both well-defined and fading segments.

C - Colour Variability/Change

A melanocytic naevus usually has a single shade of colour, two colours with one occurring inside the other, or regularly repeated shades such as tan, brown, or pink.

In the majority of cases, melanoma can be brown, but it may also present with five or six colours, such as black, blue, tan, grey, pink, and red. These colours are irregularly or unevenly distributed.

D - Different

The majority of people have a "signature naevus", meaning that all their melanocytic nevi resemble each other. Melanoma, by contrast, appears as a unique lesion that looks different from all other lesions.

A pigmented lesion that looks different from others is often called the "odd-mole-out" and should be considered suspicious even if it does not necessarily fulfil all ABCDEFG criteria.

E - Evolving / Elevated

A melanocytic naevus is usually stable and does not change over time in terms of size, colour, or shape. In melanoma, such changes may be noted over the course of several months to years.

In the EFG acronym, 'E' also stands for Elevated. Benign lesions such as dermal naevus, cyst, or dermatofibroma can be elevated, but any new elevated or thickened lesion may be considered suspicious for nodular melanoma or another form of skin cancer.

F - Firm

Benign lesions such as dermatofibroma may feel firm, but this feature is also common in nodular melanoma.

G - Growing

A nodular melanoma can grow rapidly, with noticeable changes occurring over a duration of several days to weeks. Benign skin lesions usually remain stable or change very slowly over years to decades, though their appearance may change rapidly over a few hours in cases of inflammation, injury, or eczema.

Limitations of the ABCDEFG Criteria

The ABCDEFG criteria are not used exclusively for melanoma, as some of the criteria may also be displayed by other types of skin cancer, such as pigmented squamous cell carcinoma and basal cell carcinoma.

Melanocytic naevi can change under special circumstances, such as darkening after sun exposure, during pregnancy, and with age. Lesions such as solar lentigines and seborrhoeic keratoses also routinely change over time.

The ABCDEFG criteria have been shown to be helpful in identifying a potential melanoma; however, the criteria are not efficient or reliable in recognising all melanomas. For example, the criteria are not helpful in identifying less common subtypes such as melanoma in childhood and desmoplastic melanoma, as these lack the features identified by the ABCDEFG criteria.

Melanoma is a serious form of skin cancer that can progress quickly. It is treatable when identified at early stages. If a lesion is left untreated, it may spread to other parts of the body and become life-threatening.

Any skin lesion displaying ABCDE or EFG features should be assessed by a dermatologist as soon as possible.