The ABCDE method for monitoring your moles.

A mole that poses no risk generally adopts a well-defined shape, often round or oval, with a marked symmetry between its two halves. When you examine your moles, try to imagine a line passing through the centre of each one: if it is possible to divide a mole into two equal parts, then it is likely that it is a benign spot.

However, if one half is significantly different from the other, or if the mole as a whole presents a distinctive shape, this should raise concern as it may be a melanoma.

A blurred boundary of a mole is suspicious. Indeed, traditional moles have clear, well-defined edges and are distinctly separated from the rest of the skin. Conversely, it is not uncommon for a melanoma to exhibit blurred or jagged edges, as if the pigment inside had migrated into the adjacent epidermal regions.

This irregularity of the edges is concerning as it indicates an excessive proliferation of melanocyte cells, which no longer adhere to the classic structure of a skin mole. The sharpness of the edges of skin moles is an important characteristic to monitor as a loss of regularity is often present from the early stages of a melanoma.

A mole that is healthy typically has a uniform colour, ranging from light brown to black, depending on your phototype. Occasionally, congenital moles may exhibit slight variations, but overall, the shade remains stable.

This is not the case with melanomas. A lesion taking on different colours and having a black, brown, red, blue, or even white hue, may indicate a malignant character. These colour variations reflect abnormalities in the production of melanin and a potential degeneration of skin cells. Thus, the sudden appearance of new shades within a nevus or the development of a new mole with a non-uniform colour is a warning sign.

Another factor to monitor is the size of a mole. Generally, benign moles have a diameter less than 6 mm. Melanomas, on the other hand, tend to be larger, especially as they progress. That's why if a mole grows rapidly and exceeds the size of a pencil eraser, which is about 6 mm, careful monitoring is necessary.

Finally, the last criterion evaluated by the ABCDE method is the evolution of moles. A change in appearance over a few weeks or months of a mole is a sign not to be overlooked. Any change is significant, whether it's the size, shape, colour, or texture of a mole. Similarly, if a mole becomes rough, starts to bleed or causes itching, a quick consultation with a professional is necessary. Stability is a key element of moles: benign moles do not change or change very little over time.

If you notice that one of your moles exhibits any of these characteristics, it is crucial to seek a dermatologist without delay. The earlier a melanoma is detected, the better the chances of recovery.

• KOPF A. W. & al. ABCDE - An Evolving Concept in the Early Detection of Melanoma. JAMA Dermatology (2005).

• SMITH BEGOLKA W. & al. Early detection of melanoma: Reviewing the ABCDEs. Journal of the American Academy of Dermatology (2015).

• American Academy of Dermatology Association. What to look for: ABCDEs of melanoma.