CAN and DN are clinicopathologic markers of patients at an increased risk for melanoma. Patients with CAN/DN should be screened regularly for melanoma.
CAN are not obligate precursors to melanoma, and they do not have to be removed—they may be clinically monitored for change.
The majority of melanomas are believed to arise de novo, and are not associated with a precursor nevus.
A biopsy of a pigmented lesion is performed if there is a high level of suspicion for melanoma. Other reasons for biopsy may include irritation, cosmesis, or atypical lesions in areas difficult to self-monitor.
An excisional biopsy is the preferred method to remove any lesion concerning for melanoma to provide the most accurate diagnosis and smallest risk of recurrence.
Reexcisions need not be performed in mildly and moderately DN with clear margins on the original biopsy.
Mildly DN with positive histologic margins and no clinical residual pigmentation can be safely observed.
Observation of moderately DN with positive histologic margins and no clinical residuum may be reasonable, but more data are needed.
Severely DN with positive histologic margins should be reexcised.
Pitfalls and Cautions
While the morbidity of a biopsy should always be considered, there is no substitute for biopsy in cases where a true concern for evolving melanoma exists.
Serial photography has no impact on the development of melanoma unless the clinician has a low threshold for biopsy for any evolving CAN.
Patient Education Points
Patients should be taught that all CAN do not evolve on to melanoma, and that they represent a marker of melanoma risk rather than a “precancer.”
Therefore, most CAN may be monitored clinically as long as there is no evolution and they appear similar to the patient’s other CAN.
The decision of whether to code a shave as a biopsy or shave removal is based on the surgeon’s intent. Even a deep, broad scoop shave, if performed to biopsy the lesion in question, should be coded as a biopsy.
Clinically atypical nevi (CAN)/dysplastic nevi (DN) are a subset of melanocytic nevi that clinically have an irregular, poorly defined border, asymmetric shape, and variegated pigmentation, and are generally larger than 5 mm.1 When biopsied, these lesions have certain histologic findings including disorganized melanocytic proliferations and associated atypical cells.2 Although CAN/DN themselves are not obligate precursors to melanoma, they are clinicopathologic markers of patients with an increased risk for melanoma.3,4 Some patients that have numerous CAN/DN can be challenging to follow clinically and may require surgical procedures for lesions suspicious for melanoma.
William Norris, a Scottish surgeon, reported the first case of cutaneous melanoma in 1820. He also ...