How to Assess Skin Lesions for Risk of Cancer

How to spot skin cancer with abcde rule

During this course you will be introduced to the principals of assessing photographs of skin lesions for worrying features

This will include considering the text details that patients have provided about how a skin lesion may be behaving or changing

A useful approach to assessing any photograph of a skin lesion is to use the 'ABCDE criteria'

The ABCDE criteria offer a systematic way of assessing a skin lesion according to its appearance and behaviour

Positive findings when using the ABCDE criteria will usually indicate that a face-to-face appointment to examine the skin lesion in person is appropriate

The ABCDE criteria are most useful for assessing lesions for the risk of cutaneous melanoma

The particular features of non-melanoma skin cancers will also be discussed during the course

The ABCDE rules are particularly useful for spotting the warning signs for cutaneous melanoma but may also be helpful for assessing non-melanoma skin cancer given that skin cancer share common pathological clinical features

Please click on each letter of the algorithm below to learn more:

If a patient has any of the ABCDE signs, they should be seen by their GP

A is for Asymmetry

  • The majority of melanomas and NMSCs are asymmetrical
  • If a line is drawn through the middle of a skin lesion and the two halves are not the same this should raise concern in the examiner and the patient should be seen for face-to-face assessment by history and examination

B is for Border

  • Melanomas tend to have poorly defined, jagged, scalloped edges, unlike benign moles that have smooth, well-defined borders
  • NMSCs also tend to have uneven borders which often look crusty or ulcerated
  • All lesions with irregular borders should raise concern in the examiner and the patient should be seen for face-to-face assessment by history and examination

C is for Colour variability and/or Changing colour

  • Melanomas tend to have many colours that can vary from pale pink to dark brown and black
  • As these lesions grow, red, blue and white can also appear and they can look inflamed
  • Benign moles, however, tend to have a more uniform colour
  • Therefore, change in colour within a skin lesion, particularly when compared to other moles on the same individual, should raise concern in the examiner and the patient should be seen for face-to-face assessment by history and examination
  • Unlike melanoma, NMSCs tend to be unpigmented lesions and often present as persistent open sores which are pink/ red in colour eventually bleeding/ crusting therefore persistent unpigmented 'sores' are also concerning

D is for Diameter

  • Melanomas are usually larger than 6mm in diameter (the size of a pencil eraser)
  • While large lesion size is not pathognomonic for cancer, growing skin lesions should raise concern in the examiner, SCC in particular is known to rapidly enlarge, and the patient should be seen for face-to-face assessment by history and examination

E is for Evolving (changing)

  • All skin cancers are evolving lesions, changing in colour, shape and/or size
  • Other changes include ulceration, bleeding, becoming itchier and becoming crusty
  • Normal moles do not usually undergo these changes
  • Therefore, a skin lesion which is changing should raise concern in the examiner and the patient should be seen for face-to-face assessment by history and examination

Other methods that can be used to assessed pigmented lesions include:

  • 7-point weighted checklist
  • “ugly duckling” rule
  • C.A.S.H. acronym
  • Menzies method
  • CHAOS and clues method
  • BLINK algorithm
  • TADA acronym
ABCDE criteria info from https://dermnetnz.org/topics/abcdes-of-melanoma
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