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c10t3P1: this is a fairly typical pattern of lentiginous and junctional growth in the epidermis in the “radial growth” of an ALM. The papillary dermis is widened and fibrotic; it contains perivascular infiltrates of lymphoid cells. Atypia is moderately severe.
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c10t3P2: at lower magnification, the lentiginous patterns are prominent. Inflammation in the papillary dermis is moderate. The upward migration of cells into the epidermis is marked by “lacunar” patterns. The epidermis shows a prominent hyperplasia of the superficial unit.
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c10t3P3: the variable pigmentation is not simply a change induced by the environment; oxidation-reduction potentials occasionally have been cited as having an influence on pigmentation. In this field, the pigmented cells tend to be arranged in the pattern of rounded nests. The non-pigmented portion is characterized by fascicular patterns. It would appear than the polymorphism is dependent on representation of distinct clones of neoplastic cells. The solid patterns are typical vertical growth-like but in characterizing the vertical growth component, attention must be paid to patterns at the advancing margins.
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c10t3P4: this is another example of multi-micro-nodularity in the reticular dermis at the advancing margin of ALM. In the micronodules, the cells have nevus cell-like qualities, and are collected in rounded nests. The fibrous matrix of the reticular dermis is present among the micronodules. Inflammation is not a feature. Although nodularity is a feature, this is not the pattern of typical vertical growth; it is a variation of migrant vertical growth.
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c10t3P5: irregular, migrant or diffuse vertical growth is represented at the advancing margin. The cells are spindle shaped; the patterns are fascicular. Fascicles are closely aggregated. Inflammation is not a feature.
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c10t3P6: fascicles of neoplastic cells infiltrate the reticular dermis among collagen bundles. The lesion is rather bland cytologically; it has minimal deviation qualities; the absence of inflammation adds to the deceptive histologic qualities.
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c10t3P7: the bland cytologic features, the absence of inflammation, and the lack of stromal response combine to contribute to the minimal deviation nature of this ALM.
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c10t3P8: in this example, the cells are plump; they are rounded (“epithelioid”), or polygonal; they have dendritic processes. They are loosely attached to their neighbors; the features might be characterized by some observers as “spitzoid,” but this is a variation in ALM. Some of the cells show a para-nuclear vacuole, providing a “rhabdoid” quality. The condensation of fibrous tissue at the periphery of many of the nests provides a nevus-like quality to the pattern.
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