Dermatology Case Studies

Clinical Assessment of a Lesion

They have attached a photograph of the mole:

Figure 7: New mole on calf

You assess this photograph according to the ABCDE criteria, a very useful system for examining most skin lesions

Click each of letters of the mnemonic to reveal the assessment:

A is for Asymmetry

A melanocytic nevus is usually symmetrical, whereas melanoma is often irregular or asymmetrical in shape and/or colour
In this case you can clearly see the mole is asymmetrical

B is for Border irregularity

A melanocytic nevus (harmless mole seen in previous scenario) has smooth, even borders, whereas a melanoma often has irregular, blurry, or jagged edges and hard-to-define border
In this case you can clearly see the photograph shows a mole with an irregular border

On careful inspection, the pigmented component of a flat melanocytic nevus fades out towards the edge, whereas the edges of a solar lentigo or a seborrheic keratosis are well defined
You can see photographs of these types of lesions in other scenarios
The edges of a melanoma tend to have both well-defined and fading segments, as you can clearly see in the photograph this patient has submitted

C is for Colour variability and/or Changing colour

A melanocytic nevus (benign mole) usually has a single shade of colour or two colours with one occurring inside the other or regularly repeated (generally pink, brown, or tan)
You can clearly see the variation in light and dark colour in the photograph the patient has submitted

D is for Different

Most people have a 'signature nevus' - all their melanocytic nevi resemble each other
A melanoma appears unique and very different from the patient's other lesions
A pigmented lesion that is obviously different from the others is sometimes called an 'ugly duckling', 'black sheep', 'lone ranger', or 'odd-mole-out' and must be considered suspicious even if it does not fulfil the ABCDE criteria
A useful question to ask if you are facing this patient face-to-face is "How similar is this mole to your other moles?"

E is for Evolving (changing)

A melanocytic nevus 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
In this case the patient is telling you that this mole is new, and she thinks it has changed in the last few weeks
These are both concerning points in the history