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In the examples at tier 3 that are “progeny” of this chapter, one lesion, showing Spitz-like qualities, is characterized by cytologic atypia, and by a vertical growth-like pattern (c20t3P1-8). In the stroma of this lesion, there are markers for host immune response with lamellar fibrosis. The lentiginous and junctional component extends in the epidermis away from the dermal component; this is a common feature of deviant Spitz-like lesions. As is often the case for lesions in this category, a nodal metastasis has been documented, but the incomplete history precludes a statement regarding the later clinical course.
One lesion shows a nodule in the background of a common nevus. In the nodule, nests of cells are not back to back, but the lesion in its symmetrically expansile patterns can be qualified as showing typical vertical growth (c21t3P1-4). The cytologic features and the stromal changes are not those of a nodular combined nevus. The history is incomplete, but I believe that this lesion is from the forehead of a 14 year boy, and that the course of disease was progressive.
A recurrent lesion is represented. The primary lesion shows nevoid minimal deviation patterns (c22t3p1-7). Focally, the degree of cytologic atypia is marked, and the cells have “epithelioid” features. The patterns in the recurrence are those of a scar with a dermal nodule; the pattern in the recurrence is not that of a “primary configuration.” As is often the case, the cells of the recurrent lesion are cytologically atypical and monotonous (c23t3P1-4).
Some of the lesions show patterns of partial regression. For some observers, it seems that regression is a prognostic parameter, rather than a marker for an area in which verical growth component has lost its right of domain, and has been eliminated by the host immune response (c24t3P1-4). Perhaps, the immune response in altering the relationship between neoplastic cells and stroma might facilitate the release of some of the viable neoplastic cells into the circulation.
The host immune response is variably represented in this material. In many of the common nevus-like MDM, the host immune response is poorly developed. This lack of both inflammation, and stromal lamellar fibrosis produces a rather bland pattern, a pattern that might, with a casual examination, be mistaken for that of a common nevus.
In some of the lesions, the host immune response is cellular; the relationships between neoplastic cells and lymphocytes takes on the qualities of halo nevus-like reaction.
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