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Dermatopathology: Practical & Conceptual April - June 2007
4. New Heights: Most “large dysplastic nevi” are really small congenital nevi!
Yaqin Zhang, M.D.
A. Bernard Ackerman, M.D.
superficial congenital nevus
How did it happen that those authorities on proliferations of melanocytes of all kinds (i.e., Clark and those who were coworkers or otherwise followers of him), for example, Tong, Murphy, and Mihmwho, in 1988, would continue to proclaim that which had been declared by Clark et al. for nearly 10 years, namely, dysplastic nevi, on average, are about 10 mm in greatest diameter. This is what was stated by those three fellow workers:
"The dysplastic nevus as a rule differs from the common acquired nevus in its size. The common acquired nevus usually reaches a maximum diameter of 5 mm. The dysplastic nevus, on the other hand, clinically has an average size of approximately 10 mm in diameter, although much smaller dysplastic nevi and much larger ones may be observed."
] The "much larger ones" almost certainly were congenital nevi. How could they and others make such an error, to wit, confusing an acquired "dysplastic nevus" and a congenital nevus"? The reason can be stated succinctly: they had no criteria, repeatable and reliable, for diagnosis clinical or histopathologic of the so-called dysplastic nevus, to say nothing of criteria morphologic for a "superficial" congenital nevus, and, moreover, they emphasized large size of "dysplastic nevi," which usually are small. Therefore, they ended up unwittingly studying many a superficial congenital nevus that they believed to be a "dysplastic nevus."[
Clark and coworkers claimed to have studied a specific acquired melanocytic nevus designated by them, consecutively, B-K mole, large atypical mole, and dysplastic nevus. Given the premises dead wrong of Clark et al. about the nevus they eventually came to name "dysplastic" in terms of the large size of it and of the characteristics morphologic of it, to say nothing about that nevus being the major precursor of melanoma and the major risk factor for melanoma, and given the fact that most of the "dysplastic" nevi they pictured in photomicrographs actually are superficial congenital nevi, we have elected to refer to the small, flat or very slightly raised, acquired, pigmented benign proliferations of melanocytes, as "Clark's nevi" and to the larger, discernibly elevated, pigmented benign proliferations of melanocytes as "superficial congenital nevi." There is no place in our lexicon for "dysplastic nevi" because most of them, in reality, are either Clark's nevi or superficial congenital nevi.
Yaqin Zhang, M.D., is a fellow in dermatopathology at the Ackerman Academy of Dermatopathology where A. Bernard Ackerman, M.D., is Director Emeritus. This article was reviewed by Riccardo Borroni, M.D., and Valerie Goldburt, M.D., Ph.D.. Contact corresponding author via e-mail:
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