Nevi and Melanoma
Faculty: Lindsay Ackerman, MD
Dr. Ackerman reviewed the spectrum of melanocytic lesions Sunday morning. She began her discussion highlighting benign melanocytic nevi. A giant congenital nevus aka “bathing trunk nevus” is greater than 20 cm on presentation and represents a 2.5% 5 year risk for the development of neurocutaneous melanoma. Dysplastic nevi can exist in isolation or in the expression of a phenotype as in dysplastic nevus syndrome (DNS). DNS is diagnosed in an individual who presents with > 50 nevi, histologically atypical nevi and a family history of melanoma in 1 or more first or second degree relatives. Individuals with DNS have an increased risk of the development of melanoma. For example, in an individual with DNS and more than 2 first degree relatives with melanoma, there is an 85% risk for the development of melanoma before the age of 50.
Next, Dr. Ackerman reviewed melanocyte distribution in the body including skin, eyes, ears, GI tract, leptomeninges, oral and genital mucosa. Early detection is the key to survival for melanoma, a malignant tumor of the melanocytes. Detection is best done through a thorough clinical exam, identification of lesions utilizing the ABCD and “ugly duckling” sign, dermatoscopy, clinical photography and history. A biopsy of a lesion that is suspected to be a melanoma must be a representative portion of the lesion with adequate depth to allow staging. Spread of melanoma occurs through hematogenous or lymphatic spread. Melanoma prognostication is based on depth and presence of ulceration.
The environmental risk factors for the development of melanoma were reviewed by Dr. Ackerman. These risk factors include intense intermittent sun exposure, chronic sun exposure, people who live at equatorial latitudes, those who have had PUVA treatment, tanning bed users and individuals with immunosuppression. Data suggest UVA exposure promotes the growth of melanoma. It is important for individuals to protect themselves daily from UVA exposure (such as through light from car windows). In addition to physical sunscreens which reflect UVA and UVB rays, Dr. Ackerman recommends protection with hats and UPF clothing.