Diagnosis: Dysplastic nevus with severe atypia

The histology of our second case revealed dysplastic nevus with severe atypia. The presence of nevus cells on the lateral margin of a dysplastic nevus with severe dysplasia requires wider excision. In addition to that nevus, four other abnormal-appearing moles were excised at the patient’s return visit. The pathologist reported two dysplastic nevi with moderate atypia and two with severe atypia. Given the clinical picture, I have asked a surgeon to remove all nevi that are >10 mm in diameter and those that are a mixture of tan, brown, and pink. I also will follow the patient in my office.

With respect to our two cases, there was not much clinical difference. No one feature or test declares that a mole has turned malignant, and the clinical features suggesting abnormality are not always obvious. Four warning signs include A for asymmetry, B for border (smudgy, ill-defined borders may spell trouble), C for color (variegated colors, dark brownish-black hues, as well as red or white areas within a mole make it suspicious), and D for diameter (if >0.6 cm). Also, pigment cells within a mole that seem to be overactive, such as a dark dot or streak, may suggest a need for biopsy.

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It’s a good idea to take photos (or video) so you can watch for changes in moles. Crusting, erosion, oozing, or bleeding are also signs of possible trouble. Congenital nevi that are >1.5 cm or very dark pose a risk of developing melanoma. New moles appearing after age 40 are slightly suspicious by history alone.

Currently, the gold standard for diagnosing melanocytic neoplasms is by histopathologic examination. Although dermatopathologists note that “dysplastic nevi cannot be considered a distinct clinicopathologic entity because histologic dysplasia is found in a range of nevi that may or may not show clinical atypia,”7 the pathologist who reads the slide has the final word in interpreting a mole’s tumor potential.

Almost all dermatopathologists presently label dysplastic nevi by degrees of mild, moderate, or severe. The grading is done on the mole’s cytology and architecture. If read as moderate or severe by either parameter, total removal of the mole is recommended. Most pathologists state the need for further removal in the final report. Given the lack of specific criteria for histologic reading of this entity and the variation among pathologists on mole terminology, it is best to confer directly with the physician who read the slides if there is any confusion.

In defense of pathologists, lawyers and the lay public often fail to accept that a level of uncertainty exists with the reading of pathologic slides. Thus, underreading of mole severity can lead to litigation based solely on poor clinical outcome. As a result, there will always be a tendency to overread. In other words, a pathologist who follows common and accepted methods of reviewing, interpreting, and reporting the findings and who fulfills the standard of care in specimen processing may still be safer to overread. This is especially true with “dysplastic nevi” in which no firm criteria clearly classify moles as benign or malignant. Pathologists would rather speak of a continuum or spectrum of melanocytic neoplasia and the challenges inherent in microscopic interpretation. 

Thus, neither of these two clinically worrisome moles proved to be melanoma histologically. With melanoma, the key to success is prompt removal before the lesion spreads to internal organs, so it behooves the clinician treating a suspicious lesion to know what each pathologist means by “atypical nevi” and the difference between mild and severe dysplasia. 

Dr. Burkhart is clinical professor of dermatology at Medical University of Ohio at Toledo and clinical assistant professor of dermatology at Ohio University College of Osteopathic Medicine, in Athens.

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