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The problem lesion can be identified in part as having features of a common dermal nevus. A lentiginous and junctional component showing mild to moderate atypia is also represented and the combined features of
this portion of the lesion might be characterized as some variant of atypical nevus. The real images of the histologic sections are lacking in markers for host immune response and on this basis, the lesion might be
qualified as an atypical nevus of indeterminate type (the lesion cannot be characterized as a common atypical nevus as seen in the dysplastic nevus syndrome in the absence of convincing host immune response).
One lesion that is distinguished from common premalignant dysplasias is atypical halo nevus; the distinctive immune response of the halo nevus sets it apart. It would seem appropriate to eliminate lesions of both
the dysplastic nevus and the halo nevus-like categories from our differential diagnosis. On the other hand, the current definition of the halo nevus-like category may be incomplete. In the halo nevus-like category,
some patients have multiple lesions. In the setting of multiple halo nevi, some of the lesions are peculiar melanocytic dysplasias showing a somewhat distinctive form of cytologic atypia but almost totally devoid of
markers for host immune response. These lesions might be characterized as halo nevus-like dysplasias ab inflammation. Halo nevus-like variant cannot be totally dismissed in our evaluation of the problem case.
In the dermal component of our problem lesion, where common nevus cells are arranged in common nevus-like patterns, there are two disparate patterns. One consists of a column of atypical cells in continuity with a
junctional component (P1- 4). A few lymphocytes are represented among the atypical cells. The pattern might be compared to those of the epidermal melanocytic
dysplasias of some atypical halo nevi. A rounded nest of atypical cells and sparse lymphoid infiltrates in the dermal component of the nevus-like component comprises the other disparity (P1-8 ). For the latter component, we might promote some type of halo nevus-like variant of dermal type but the cytologic features are not strikingly epithelioid (see WHITHERS1, 2, & 3, AND INDEX3). In an immediately adjacent field, cells are nevus-like but show mild atypia and are arranged in patternless sheets (P1-7 ). In considering the appropriateness of a characterization of this component as an emerging vertical growth pattern, only the mild atypia of the
component cells in this area would make such a characterization premature.
In the real images of the components which have been considered up to this point, there is little to evoke the virtual images of a Spitz variant. The cytologic features would offer little support; the overall
patterns are relatively non-descript.
The patterns in the left-hand portion of the digital images (P2-1) can be accommodated by the parcel of virtual images which are required in the definition of
variant vertical growth. If we compare this component to the nevus-like component discussed above, there is cytologic dysparity and the closely clustered fascicles of atypical cells in the dermis provide tumoral
qualities. All that is lacking is faith in the utility of the concept of MDM; the observer must provide this ingredient. If there is a MDM of halo nevus-like type ab inflammation, then we might accommodate the real
images of the problem case in such a fanciful category.
Most observers would have stores of virtual images for the evaluation of the real images of a Spitz nevus; in reviewing the images of the problem case, many of these observers would be able to accommodate the
problem lesion in their Spitz nevus category. Such a compromise would be an exposition of the non-specific character of the virtual images many of us have in our stores, relevant to the diagnosis of Spitz nevus. We
have comtaminated the category to such an extent that it has become difficult to be comfortable with an unqualified diagnosis of Spitz nevus. In fact, the real images of the problem case have only a superficial
correspondence with the virtual images of a classically defined Spitz nevus. A diagnosis of Spitz nevus for the problem case would require a distortion of specific Spitz nevus-like virtual images, if ambiguous real
images of the problem case and evoked virtual images relevant to the diagnosis of Spitz nevus are to find congruence.
Recognizing the ambiguities in the patterns of the problem case, it would seem most appropriate to characterize the problem lesion in a nevoid category. In view of the rather bland, uniform nuclear qualities, the
diagnosis might be refined by qualifying the lesion as a Nevoid MDM. In the portion showing features of a vertical growth-like component, the measurement by Breslow’s criteria in the area selected was 2.2 mm, and
the lesion in this same areas had extended to level IV (i.e., invasion of the reticular dermis in migrant variant vertical growth patterns). In this minimal deviation category, cautions must be appended to the
evaluation of the vertical dimensions. It would be inappropriate to assume that the measurement by Breslow’s criteria has significance in the same manner as would a similar dimension in the category of one of the
common melanomas. We have not defined a phenotype; the phenotype has ambiguous qualities.
DIAGNOSIS: NEVOID MINIMAL DEVIATION MELANOMA (AMBIGUOUS PHENOTYPE; VARIANT AND MIGRANT VERTICAL GROWTH PATTERN; LEVEL IV INVASION; FASCICULATED, SPINDLE CELL VARIANT; 2.2mm IN VERTICAL DIMENSIONS; ATYPICAL
NEVUS-LIKE COMPONENT OF INDETERMINATE TYPE; MELANOCYTIC NEOPLASIA OF INDETERMINATE MALIGNANT POTENTIAL).
NOTE: In this borderline category, the measurement by Breslow’s criteria is of questionable validity as a guide to therapy and prognosis. A conservative reexcision is recommended. Some consideration should be
given to a sentinel lymph node biopsy. The patient should be carefully examined and followed.
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