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The evidence for the effectiveness of targeted early detection by screening clinics and dermatologists is inconclusive. The limited evidence suggests that targeted screening for melanoma in the UK will be hampered by difficulties in accurately identifying the target population. Strategies to improve skin self-awareness rather than screening should be developed and evaluated.

Distinguishing malignant melanoma from benign naevus is often difficult, even for experienced dermatologists. The macroscopic clinical ABCD rule and the Glasgow seven-point checklist are helpful but are often inaccurate, yielding many false-positive and false-negative diagnoses. A Danish meta-analysis of 11 studies reviewed the efficacy of dermatoscopic diagnosis of cutaneous melanoma. Dermatoscopy performed by a trained physician was shown to increase the diagnostic accuracy to a sensitivity of 80%.43

A French meta-analysis compared dermoscopy with diagnosis by the naked eye. Eight of the 672 studies retrieved according to specific criteria were included in this meta-analysis. The selected studies represented 328 melanomas (mostly less than 0-76 mm thick) and 1865 mostly melanocytic benign pigmented lesions. For dermoscopic diagnosis of melanoma the sensitivity and specificity ranges were 0-75-0-96 and 0-79-0-98, respectively. Dermoscopy had significantly higher discriminating power than clinical examination, with respective estimated odds ratios of 76 (95% CI 25, 223) and 16 (95% CI 9, -31) (P = 0-88), and estimated positive likelihood ratios of 9 (95% CI 5-6, 19-0) and 3-7 (95% CI 2-8, 5-3), respectively.44

A further study to test the effectiveness of dermatoscopic diagnosis used patients referred to a pigmented lesion clinic by their general practitioner. These patients had melanocytic lesions requiring excision (using dermatological criteria). A set of 74 sequentially observed lesions -37 melanomas and 37 melanocytic naevi - made up the initial set. A second set of 52 lesions - 32 melanomas and 20 melanocytic naevi - was used to validate conclusions drawn from the original set. The clinical features studied were appearance, history and dermatoscopic features. Following pathological examination, both sets of lesions showed that the most powerful identifying effect of the lesion was the presence of three or more colours on examination by dermatoscopy. In the initial set the age of the patient and the irregular edge and largest diameter of the lesion also

Is dermatoscopic diagnosis more accurate as a diagnostic tool than examination by the naked eye?

contributed to diagnosis, but these were less useful in the second set. The sensitivity and specificity of the three-colour dermatoscopy test for melanoma and naevus were 92% and 51% respectively (the predictive value of a diagnosis of melanoma if three colours are present is 64%, and the predictive value that the lesion will not be melanoma if less than three colours is 85%), with the potential to reduce minor surgical work and patient morbidity.45

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