Question 1

Does the ABCDE rule apply to all types of melanoma?

Accepted Answer

No — nodular melanoma may present as a symmetric, uniformly coloured papule. Amelanotic melanomas lack pigment entirely. The 'E' (Evolution) and 'ugly duckling' sign are most sensitive in these cases.

Question 2

What is the sensitivity and specificity of ABCDE?

Accepted Answer

Pooled sensitivity 57–90%, specificity 36–100% depending on the threshold. Using ≥3 features yields higher specificity but lower sensitivity. Dermoscopy increases sensitivity by 20–30%.

Question 3

Should I biopsy every lesion with ≥3 ABCDE features?

Accepted Answer

Yes — excision biopsy with histopathology is the gold standard for clinically suspicious lesions. ABCDE is a screening tool, not a substitute for histology.

Question 4

How should I incorporate the 'ugly duckling' sign?

Accepted Answer

The ugly duckling sign (a lesion that looks different from the patient's other moles) is complementary to ABCDE, particularly useful in patients with many atypical moles.