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Make the Diagnosis: Melanoma

Prior Probability

The lifetime risk of melanoma is 1.7% for US white men and 1.3% for white women,7 which means that the probability of melanoma at any given point is less than 1%. Thus, for the US patient at average risk, the prior probability of melanoma can be conservatively taken as 1%, although the true point prevalence is likely much lower. Other populations have different risks. For example, the incidence of melanoma in the United States was 13.3 per 100 000 in 1995 vs 55 per 100 000 in Queensland, Australia.4

Population for Whom Melanoma Screening Should Be Considered

  • Atypical (dysplastic) nevi

  • Family history of melanoma

  • Personal history of melanoma

  • Multiple nevi

  • Fair-skinned patients, especially those with sun sensitivity or proclivity to sunburns

  • Large congenital nevus

  • Immunosuppression

Detecting the Likelihood of Melanoma

Table 29-9.Likelihood Ratios for Any One Finding From the ABCD(E) Criteria and the Individual Findings

Reference Standard Tests

Biopsy with histopathology.

Original Article: Does This Patient Have a Mole or a Melanoma?

Clinical Scenario

A patient presenting to your office informs you that he is concerned about a mole on his arm. Although he is not sure how long the mole has been present, he tells you that recently it has enlarged and looks different. As you begin the examination, you also notice the presence of several other moles and ask yourself, is this lesion a benign mole or a malignant melanoma?

Why Is This an Important Question to Answer?


The incidence rate of malignant melanoma, once considered a rare malignancy, has increased dramatically in recent decades. In 1930, the lifetime risk of an individual in the United States developing melanoma was 1 in 1500. Estimates placed the lifetime risk in 1996 at 1 in 87, with 1 in 75 by 2000.1 This increased incidence is important because, unlike the more common nonmelanoma skin cancers (basal cell ...

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