THE ABCD-RULE OF DERMATOSCOPY (STOLZ) AND RISK STRATIFICATION (RS) (KENET)

THE ABCD-RULE OF DERMATOSCOPY (STOLZ) AND RISK STRATIFICATION
(RS) (KENET)

The ABCD-rule is an evaluation method of dermatoscopy based on identification a number of signs and findings which are multiplied by a correction factor to establish a total dermatoscopy score (TDS) of the lesion. If the TDS of a melanocytic lesions is between 4.75 and 5.45 it is a possible melanoma, if above 5.45 it is a probable melanoma (11).

The sensitivity of the ABCD rule was originally reported as high as 98%. Others have found sensitivities between 59% and 88%.

Pattern analysis dermatoscopy which looks for specific signs of malignancy, such as the RS method, has been tested in a Danish study which resulted in an "expert" sensitivity of 83% and a specificity of 94%. It was found that clinicians trained in dermatoscopy significantly improved their skill by dermatoscopy (P<0,05), whereas untrained clinicians did not (Figs 22 and 23) (8). The ABCD rule works well with thin melanocytic lesions whereas nodular melanoma tends to be missed (9). A comparison of the ABCD rule and RS has recently been performed and both methods were found valuable in the diagnosis of malignant melanoma. By RS, experts obtained a higher diagnostic accuracy than by the ABCD rule (10).

Entry forms for the RS method and the ABCD rule are shown in Figs 24 and 25. We use both methods when evaluating pigmented skin lesions.

CONCLUDING REMARKS

In trained hands dermatoscopy is highly specific, but remember that the method is better to rule in than to rule out malignancy. Therefore, if in doubt, take the lesion out. Excision biopsy in suspicious cases is the golden standard. In dubious cases follow-up visits are indicated. False positive and false negative dermatoscopic diagnoses will occur. This should not discourage the use of the method. No clinical diagnostic method has sensitivity of 100%, but dermatoscopy can be improved by continuous education and regular use.

The high specificity of dermatoscopy is a valuable help in a dermatologist’s clinical work by reducing the number of unnecessary excisions of benign skin lesions, hereby sparing pain, cost and time.