Review Question - QID 103812

This man has a lesion concerning for melanoma. The most important prognostic factor in melanoma is the Breslow thickness, the depth of invasion of the lesion.

Melanoma is a treatable cancer if discovered early in its course. The 10-year survival rate of a lesion with a Breslow thickness < 1mm is 94%. However, if a lesion is already relatively deep when discovered, the survival rate plummets. When the Breslow depth is > 4mm, the 10-year survival is only 40%.

Shenenberger discusses cutaneous malignant melanoma from the perspective of a primary care physician. He notes that while melanoma accounts for only 3-5% of all skin cancers, it is responsible for approximately 75% of all deaths from skin cancer. An increased number of moles, dysplastic (i.e. atypical) nevi, or a family history of melanoma are all risk factors for developing melanoma.

Tran et al. describe the diagnosis of malignant melanoma and note that dermoscopy can be a useful tool to increase the accuracy of a dermatologist in diagnosing a melanoma by 10-27%. Traditional diagnosis, as well as staging, is done by biopsy.

Image A shows an example of melanoma. Note the irregular coloration and borders.

Illustration A depicts the Breslow depth and contrasts that with Clark's levels, an alternative way to measure depth.

Incorrect Answers:
Answer 2: While atypical or dysplastic cells are a useful indicator of prognosis in some other cancers, overall depth of invasion is a more important indicator in malignant melanoma.
Answer 3: Patients older than 65 have a worse prognosis than their younger counterparts, but age is a weaker predictor of prognosis than Breslow thickness.
Answer 4: Although ulceration and pruritis are signs of melanoma and do indicate a worse prognosis, Breslow thickness is a stronger indicator.
Answer 5: A patient with a family history of skin cancer is at increased risk of developing skin cancer, but this is not a useful way of determining prognosis of a new cancer.