Dermatologists depend on overall pattern recognition and comparison rather than specific analytic criteria to distinguish melanoma lesions (malignant skin cancer) from harmless skin moles, according to an article in the April issue of Archives of Dermatology.
Early detection is the key to reducing the death rate from melanoma, but most people, including general practitioners, are not able to distinguish melanoma from harmless moles, according to background information in the article. Helping people to detect their own melanoma in the past has relied on analytic formulas like the ABCD rule, which teaches looking for A, asymmetry; B, irregular borders; C, uneven color; and D, diameter. The authors suggest that assessing how dermatologists spot melanoma may offer better ways of teaching the general public what to look for and to use to develop a training model for general practitioners.
Julie Gachon, M.D., of the Hôpital Ste. Marguerite, Marseille, France, and colleagues assessed dermatologists' recorded immediate perceptions as well as their intuitive diagnosis of 4,036 either harmless or malignant moles (lesions) that they had decided to remove for any reason and compared that information with the final diagnosis of the lesion based on a laboratory analysis. One hundred-thirty-five dermatologists, most of whom were community physicians in private practice, recorded their overall impression of the lesion, based on their past experience; assessed the lesion using the analytic ABC criteria; recorded their impression of how different the lesion was from the patient's other skin moles (the ugly duckling sign); and noted how the lesion had changed, according to the patient. The physicians completed a second part of the questionnaire after they obtained the pathology report.
Of the 4,036 lesions removed, 1,634 were removed (40.7 percent) for aesthetic or functional reasons, 535 (13.3 percent) "only to reassure the patient", 1,199 (29.7 percent) because the dermatologist considered them suspicious and 869 (21.5 percent) because the dermatologist thought they might be precursors to melanoma. These different reasons accounted for two (1.3 percent), nine (6.0 percent), 141 (94.6 percent) and 14 (9.4 percent) of the 149 lesions that were determined to be melanoma.