Whithers 1

Whithers 2

Whithers 3

Desmomela

BWEEMS

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MDMLMM

Nevoid MDM

MDMhalo

Nearneoplasia

MDMhalo, metastasizing

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Pictorial 1

Pictorial 2

Pictorial 3

Pictorial 4

C4P1-1: The lesion is plaque-like at the surface of the skin; it is flat and relatively broad. The epidermis is hyperplastic and rete patterns are irregular. The papillary dermis is widened and fibrotic. It contains nests of melanocytic cells and prominent clusters of melanophages. An interface between nests of atypical cells and sheets of cells that resemble common nevus cells is identified by the red arrows. In turn, there are sheets of lymphocytes at the interface between the papillary dermis and the reticular dermis.

C4P2-2: There are lentiginous and junctional patterns in the epidermis. Some of the atypical cells have migrated upward into the overlying epidermis. Nests of cells, cytologically similar to cells forming nests at the dermal-epidermal interface are loosely but regularly spaced in the widened papillary dermis. This pattern and the regular spacing of nests in the papillary dermis is basic for the recognition of variant vertical growth components. The other requisite is a population of cells forming the nests that shows at least moderate atypia. Markers for host immune response, if represented (and not always a feature of MDM), provide an additional clue to alert an observer to the possibility that a clone of neoplastic cells other than common nevus cells is represented in the dermal component. The sheets of common nevus-like cells near the interface with the reticular dermis might be a marker for a remnant of a preexisting nevus. The limited, delicate fibrous matrix on both sides of the follicle to the right provides evidence that a portion of the lesion has undergone spontaneous regression. If we accept the dermal pattern as variant vertical growth, we have at least introduced the possibility that the respective lesion is some variant of melanoma. With this possibility in mind, there is utility in examining the patterns with the tools for prognostic evaluations of melanomas, even if we later decide to step back from an outright diagnosis of melanoma. With Breslow’s criteria, the lesion is thin (i.e., less than 1 mm in vertical dimensions); it is a good prognosis lesion and regardless of final decisions as to where along the spectrum of neoplastic progressions this lesion is to be assigned, it would most certainly qualify as a borderline melanocytic neoplasm of indeterminate malignant potential. In addition, with Clark’s criteria as modified in the concept of MDM, it would qualify as level III pattern, regardless of what the final decision as to the proper assignment might be. We could also introduce the concept of a mollifying influence of a rich component of tumor infiltrating lymphocytes but we have already conceded this possibility by characterizing the lymphoid reaction as halo nevus-like. The lesion is not ulcerated, and it is difficult to find a convincing mitotic figure. Regardless of perspective, if the lesion is assigned to the melanoma category, it additionally falls in the ‘good prognosis’ groupings (prospectively, from an evaluation of the characteristics of the primary lesion).

This is an example of a lesion that is commonly misdiagnosed initially as some type of nevus and that commonly finds it way into the forensic arbitrations and contentions. It is the type of lesion that is manipulatable with the tools in the concept of MDM but these tools have been discredited by many ‘expert’ dermatopathologists who are unwilling to admit their utility and who, moreover, are experiencing as much frustration in their attempts to categorize these problematic lesions as are the observers who look to the ‘experts’ for guidance.

C4P1-3: The lentiginous and junctional components and the variant vertical growth component (i.e., the nests of cells above the red arrows) are shown to better advantage at this magnification. In sequence, moving from the interface between the papillary dermis and the reticular dermis upward, there are two strata; the first (at the interface) is a sheet of lymphocytes and the next stratum is a sheet of pale, common nevus-like cells.

C4P1-4: The lentiginous component shows moderate to moderately severe atypia; there are occasional migrants in the overlying epidermis. If we jump the gun and take the occasional migrant as a marker for melanoma in situ, all the complex patterns in the dermis can then be ignored; the lesion is then likely to be dismissed as SSM. In this field, the cells of the dermal component are spindle shaped and are arranged in loosely spaced fascicles. Perhaps some, who have become adept in molding the images of variant, problematic lesions to fit the requisites for the diagnosis of a Spitz nevus variant, would prefer to classify this lesion as a ‘Spitz nevus’ variant. The cytologic features of the dermal component are monotonous and relatively bland; they are minimally deviant.

C4P1-5: The interface between the variant vertical growth component and the population of common nevus-like cells is represented. The nevus-like cells are peculiarly pale (a variation of balloon cell transformation?). Although acceptable as a slightly altered remnant of a preexisting nevus, we must consider the possibility that these distinctive cells are a marker for an earlier stage in the evolution of a neoplasm that only resembles a nevus in this remnant of a an earlier evolutionary stage; these cells may also be neoplastic and a representative of a step along an evolutionary sequence leading to some variant of melanoma.