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c20t3P1: This is a field from an area of “atypical nodular hyperplasia” in a giant congenital nevus. The nuclear patterns are monotonous. There is mitotic figure to the right of the center of the field. The pattern is “blastoid,” but this is not the pattern of melanoblastoma.
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c20t3P2: The upper portion of the dermis shows a zone of reactive fibroplasia in the pattern of a scar. The overlying epidermis shows an area of lentiginous and junctional “dysplasia” in pigmented spindle cell patterns. The lentiginous and junctional component is confined to the epidermis over the area of the scar; the lesion is a recurrent nevus.
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c20t3P3: At a higher magnification, the cells are heavily pigmented, and some are loosely attached to their neighbors. The spindle cells have prominent pigmented dendrites. Lamellar fibrosis, a feature so common in premalignant dysplasia is not a feature of this lesion. Often inflammatory infiltrates are minimal, as in this example.
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c20t3P4: To the uninitiated, this pattern is likely to be disturbing; it might be misinterpreted as “melanoma.” The lesion has even been characterized as “pseudo-melanoma.”
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c20t3P5: This is another example of recurrent nevus. In this field, the pigmentation of “nevus”cells is variable. The nests of cells at all levels in the scar are rounded; the cells are more epithelioid than spindle shaped. There is minimal inflammation, but some examples may be inflamed. The pattern of the scar is not that of the inflamed, laminated stroma of a premalignant dysplasia.
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c20t3P6: Some degree of atypia is acceptable in the setting of recurrent nevus.
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c20t3P7: Atypia is evident in both the epidermal and the dermal components of this recurrent nevus. Lesions showing atypia to this degree may prove to be recurrent melanocytic dysplasias rather than a common nevus. If the lentiginous and junctional component does not extend in the epidermis beyond the domain of the scar, and if the stromal changes are not characteristic of a dysplasia, the atypia is acceptable in the setting of recurrent nevus. The original biopsy material should be reviewed. The changes in this field at this magnification would be difficult to distinguish from those of a premalignant melanocytic dysplasia.
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