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MINIMAL DEVIATION LENTIGO MALIGNA MELANOMA (contributed by: Naomi Lawrence, M.D., Assistant
Professor of Clinical Medicine, Director, Dermatology Surgery (University of Medicine and Denistry of New Jersey, Robert Wood Johnson Medical School at Camden), Center for Dermatologic Surgery, Sagemore Building,
Suite 8103, 8000 Sagemore Drive, Mariton, NJ 08053
This 45 year old man had a hyperpigmented scar along the left jawline. He had had a biopsy of a skin lesion in this site in 1993 (Figs. P15-41-44). The patient’s father died of malignant melanoma. On the biopsy material from 1993, the lesion involved the deep surgical margin. It had been interpreted as an
atypical Spitz nevus. The patient returned recently with a history of having developed grey-black papules in the site of the original biopsy. The papules had appeared in this site during the preceding 6 months. A
repeat shave biopsy of the site had been performed prior to referral (Figs. P15-45-48). The respective histologic section was interpreted as melanoma. The lesion measured at
least 0.7 mm in vertical dimensions and extended to the margins of excision. The lesion was then removed following which “Moh’s micrographic surgery” was performed to obtain free margins. The patient was referred to
an oncologist for further evaluations.
At the time of this surgery and subsequently, the margins were interpreted as being free of tumor (Figs. P15-49-55).
Discussion: The clinical presentation in 1993 was recorded as a red-brown papule of the skin over the jaw. There was a history of bleeding from the site for 8
months. Some of the keywords in the pathology report include: spindle and epithelioid cells, clefts around the junctional components, mild atypia, low mitotic rate, maturation, vascular ectasia, and scanty
infiltrates of inflammatory cells. These are the intensions embodied in the parcel of virtual images that has relevance for the histologic definition of Spitz’s nevus. The lesion was qualified as atypical and
surgical margins were noted to be involved.
In an alternate approach, the patterns at the dermal-epidermal interface qualify as lentiginous and junctional. The cells of the junctional component are spindle
shaped but cytologic features of these cells (Fig. P15-42) are more in keeping with those of the actinic dysplasias (lentigo maligna and related processes). On this basis, the
peculiar and deceptive patterns might be characterized as those of a variant of lentigo maligna melanoma. The location would offer some support for this interpretation. The patterns in the dermis are unusual. There
is little evidence that the lentiginous and junctional components in their migrations into the dermis (if indeed it is the source of the cells in the reticular dermis) has induced a significant change in the stroma
of the papillary dermis. In fact, if such is the sequence, little of a population of migrating cells remain in the papillary dermis.
In view of the preponderance of rounded nests in the reticular dermis, it might be tempting to consider a variant of a common nevus in the differential diagnosis.
The nests in the dermis sit among collagen bundles and have induced little in the way of tumor stroma or host immune response. The patterns are remarkably “clean.” In areas, the nests in the deeper portion of the
dermis are smaller than those at the dermal-epidermal interface (a feature of so-called maturation).
The characterization of Spitz nevus as spindle and epithelioid nevus has unfortunate consequences. An observer who has adopted this characterization of cells as a
key to the interpretation of a problematic melanocytic lesion is likely to then extend such a characterization of cytologic features to embrace the parcel of Spitz nevus-like qualities; the step to the
diagnosis of the problematic lesion as Spitz nevus then is short. Our ability to impose virtual images (a basic trait of pathologists in the routine practice of pathology) is in large part responsible for the
commonness of the diagnosis of Spitz nevus. Our inability to accept variation in the category of common melanomas has, in turn, limited our access to parcels of virtual images having relevance for the interpretation
of those variant patterns.
We accept desmoplastic melanoma as a unique variant without acknowledging that most examples are found in the anatomic setting of actinic variants; in this
approach most examples might be characterized as variant lentigo malingna melanomas. This is an important concession; it leads to even wider definitions of melanomas - variants are introduced. One other provision in
regard to desmoplastic melanoma is important; many examples, particularly those diagnosed early on in their evolution are remarkably bland cytologically. They are so bland that the atypia of the dermal component is
likely to be overlooked; such examples are easily misdiagnosed as reactive fibroplasia or a fibromatosis. This concession to cytologic variations is a promotion of the need for a closer inspection of the character
of dermal components of problematic melanocytic lesions (i.e., something more than pattern analysis at low magnification). Such closer inspections might lead to the conclusion that there is marked variability in the
qualities of vertical growth components. For some examples, size, bland cytologic features, nesting patterns, and stromal responses are combined in patterns which may greatly compromise the ability of a pathologist
to make a diagnosis of melanoma and, consequently, may lead to diagnoses which require the imposition of improper parcels of virtual images (see Whither1, Whither 2, and Whither 3). Parcels which truly relate to variant nevi rather than melanoma
may be selected. It is in this realm of confusion, that the concept of minimal deviation finds utility.
If the reader can come away from a review of the histologic patterns of this consultation case and not appreciate the unusual and deviant qualities of the
patterns in the dermis on the original biopsy and on the recent material, then there will be no place for variant melanomas in his stores of virtual images; he will be forever at the stage of “one melanoma,
biologically and histologically.” If, on the other hand, a reader comes away with an appreciation for all that is unusual in this case, he should, with his new cautions, then search other problematic melanocytic
lesions for deviant patterns. The category of Spitz nevi might then be less attractive as a default to which a wide range of spindle and epithelioid cell lesions can be assigned.
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