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Dermatopathology: Practical & Conceptual October - December 1996
Dysplastic Nevus:: National Institutes of Health Consensus Development Conferences, 1983 and 1992— Consensus?
Daniela Massi, MD
Timothy A. Nielsen, MD
A. Bernard Ackerman, MD
Key Questions Posed by the Organizers
“Dysplastic Nevus”: Clinical Aspects
“Dysplastic Nevus”: Histopathologic Aspects
“Dysplastic Nevus”: Cytologic Atypia
Prevalence of “Dysplastic Nevi”
“Dysplastic Nevus Syndrome”
Risk of Melanoma
Management of “Dysplastic Nevi”
"Dysplastic Nevus": Histopathologic Aspects
1983 NIH Consensus Development Conference:
"Typical histopathologic features are superimposed on those of a junctional or compound nevus and include:
1. Basilar melanocytic hyperplasia with elongation of rete ridges.
2. Cytologic atypia with enlarged hyperchromatic melanocytic nuclei, often present but not essential for the diagnosis.
3. Melanocytes, spindle-shaped and arranged horizontally, or occasionally epithelioid, aggregating in nests of variable size and fusing with adjacent rete ridges to produce bridging.
4. Lamellar and concentric dermal fibroplasia.
5. Lymphocytes in patchy or diffuse superficial dermal infiltrate."
1992 NIH Consensus Development Conference:
"The lesion is generally diagnosed using histological criteria of architectural disorder with asymmetry, subepidermal fibroplasia (concentric eosinophilic and/or lamellar), and lentiginous melanocytic hyperplasia with spindle or epithelioid melanocytes aggregating in nests of variable size and fusing with adjacent rete ridges to form bridges. Frequently there is a variable dermal lymphocytic infiltration. Also helpful in the identification of these nevi is the presence of a "shouldering" phenomenon in which the intraepidermal melanocytes extend singly or in nests beyond the main dermal component."
The sets of criteria proposed by the Panels of the Consensus Development Conferences of 1983 and 1992 for diagnosis histopathologically differ from one another, and both sets are inaccurate. Diagnosis by conventional microscopy of a compound DN is made by noting the silhouette of a benign neoplasm (the most compelling signs of benignancy of a neoplasm as judged by its silhouette are symmetry and sharp circumscription), slight elevation of the neoplasm, and confinement of nests of monomorphous melanocytes to the dermo-epidermal junction and papillary dermis. Furthermore, "subepidermal fibroplasia," "lentiginous melanocytic hyperplasia," and fusion of nests of melanocytes "to form bridges" are irrelevant to diagnosis of DN; those findings may be encountered in melanomas and often are. Parenthetically, neither the Consensus Development Conference of 1983 nor the one of 1992 mentioned criteria for histopathologic diagnosis of CAN, the reason being that there is no single type of CAN, and of the several types, DN is the most common by far.
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