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Fig. c8t3p1: This drawing has been borrowed from the Whithers1, Whithers2, and Whithers3, and then modified. In the altered approach, the plane to the left gives recognition to those “Spitz-like” lesions that are represented in limited physical patterns at the dermal-epidermal interface; such lesions share features with common premalignant dysplasias; they may show focal dermal patterns that are vertical growth-like, but such a lesion would measure less than 1 mm in vertical dimensions. To the extreme right, the sphere is representative of lesions that clinically behave as common melanomas, regardless of “Spitz-like” qualities; in essence, these qualities tend to become evident as the result of retrospective evaluations. The cone between these two extremities is representative of the domain of intermediate neoplasia; this is also the domain of minimal deviation melanoma. The light gray area of the cone represents lesions of step I type. The area that is dark gray represents lesions of step II type.
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Fig. c8t3P2: In this diagramatic representation of “Spitz nevus,” common, or characteristic features are represented. Fascicles rain down from an hyperplastic epidermis into the dermis. The widened papillary dermis is edematous. Vessels are ectatic. In the reticular dermis, fascicles extend among collagen bundles. Some of the cells individually infiltrate the reticular dermis. These individual cells are smaller than those of the fascicles (maturation). Some of the fascicles are oriented parallel to the surface of the skin; these patterns may be evidence of lymphatic invasion. A nest of cells is present in the perineurium of a small nerve. Centrally, a column of fibrous tissue extends into the adipose tissue; this is a widened perifollicular sheath. Perifollicular sheaths are a favored site; in such areas, fascicles of neoplastic cells tend to be closely aggregated, and maturation is not a feature.
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Fig. c8t3P3: This is a representation of the patterns in classical MDM of “Spitz-like” type. A remnant of a “Spitz nevus” is represented on the left; infiltration of the reticular dermis and maturation are represented in this component. Centrally, the lesion is an expansile nodule in which fascicles are closely aggregated. Often, in the nodule, the stroma is specialized. Comparisons of cytologic features of the remnant on the left, and the MDM centrally would reveal discordance; generally, in the nodule, the atypia and pleomorphism is greater than in the remnant.
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