TO GO TO AN ALTERNATE EXTERNAL LINK CLICK ON ONE OF THE NAVIGATION AIDS BELOW:

MDMHALO

MDMLMM

NEAR-NEOPLASIA

MDMHALO, metastasizing

NEVOID

Pictorial1

Pictorial2

Pictorial3

NOTE: ADDITIONAL NAVIGATIONA L AIDS AT BOTTOM OF THIS PAGE

TO EXTERNAL LINKS:

WHITHERS1

WHITHERS2

WHITHERS3

DESMOPLASTIC MELANOMA

The word, NEVUS, generally has utility for the characterization of a congenital blemish or tumor, but some “nevi” may appear later in life. In part, this approach, in which “acquired” lesions are accepted in the category of the nevi, is justified by the similarities between congenital nevi and late onset (“acquired”) nevi. A nevus is organoid; in it, the patterns and relationships of adult tissue are recapitulated in distorted fashion. In this approach, nevus and hamartoma have much in common, but hamartoma more distinctly has reference not only to organoid qualities but also to tumoral qualities. The concept of a nevus embraces mesenchymal, melanocytic, and epithelial malformations. A nevus, in its native state, generally is not a progressive neoplasm, but some nevi seem to be loci minoris resistentia - sites with a predisposition for genetic alterations leading to progressive neoplasia. A NEVOID DISORDER shares some of the qualities which distinguish a nevus but, in addition, this characterization embraces phenomena such as neoplastic progressions, degrees of cytologic atypia, and host immune response. A NEVOID DISORDER may be a transient (early) stage in sequenced neoplastic progressions; the designation loses it appropriateness once the respective neoplasm begins to manifest the disarray and dedifferentiation which distinguish a “malignancy.” In reference to melanocytic lesions and current usage, these distinctions have not been rigidly observed; some melanomas in typical vertical growth patterns (i.e., lacking in organoid qualities) have been characterized as nevoid.

 For melanocytic neoplasia, the qualifier, “nevoid,” might best be avoided, if, in the respective lesion, the defining pattern is that of TYPICAL VERTICAL GROWTH . On the other hand, melanocytic lesions with both cytologic atypia and cytologic disparity, with architectural disarray, and with patterns of variant (level III patterns), or migrant (level IV patterns) vertical growth (see WHITHERS1,  2,  and   3) have some features which lend nevoid qualities to overall histologic patterns (i.e., the regular spacing of nests of rather uniform, although atypical, cells). Patterns of typical vertical growth do not exclude a precursor nevoid stage, and the two may be combined in a single lesion with the implication that one is the precursor of the other. The following problem lesion points up some of the problems in labelling melanocytic lesions, which by their deviations from common, fully developed melanomas, might be cited as having nevoid or minimal deviation qualities.

Perhaps, we might even propose, that in the characterization of morphologically borderline, thin melanocytic lesions, the qualifier, NEVOID, has application as a characterization only if variant or migrant vertical growth patterns are represented (in this usage of variant vertical growth, attention is given to a pattern without also evoking the implication that the marker is sufficiently represented to provide a clear distinction between “dysplasia” and “melanoma”). The observer is left with the choice of either of the latter two designations but having made a choice would then be obliged to qualify the lesion as a prognostically indeterminate process. For a similar thin lesion showing typical vertical growth, the observer will likely prefer to classify the lesion as MINIMAL DEVIATION MELANOMA, without feeling a need to also characterize the lesion as NEVOID . To characterize a thin  lesion as NEVOID is an admission that the patterns are of uncertain significance; that the patterns in part raise a suspicion that the lesion is a variant of a benign nevus; that the patterns do not allow for clear distinctions between those of a nevus and those of a lesion in the transitional stage of progressive neoplasia; and that because of conceptual uncertainties, the observer has been forced to make an arbitrary decision. If the definition of NEVOID MELANOMA is extended to include examples in which the patterns suggest a relationship with the variant, as well as the common nevi, then the category is nothing more than the category of minimal deviation melanoma in masquerade.

An observer, faced with the pattern in P3-1, would face a dilemma; either assign the lesion to a nevoid precursor category or assign it to a nevoid minimal deviation melanoma category. The variant vertical growth-like patterns greatly complicate attempts to make the distinction. At this magnification, the observer (with too great an emphasis on pattern analysis) might be sorely tempted to dismiss the lesion as a common nevus and go on to the next case.

P3-2: At higher magnification, the loose spacing of nests of cells in the dermis, and the rather uniform, bland cytologic features are combined to produce NEVOID patterns. The blue arrows identify many of the small individual nests which are isolated in a widened papillary dermis. Nuclei of nevus-like cells are larger near the dermal-epidermal interface than at the interface between the papillary dermis and the reticular dermis (so-called maturation).

Even at this magnification, the observer might be able to ignore cytologic deviations and merely dismiss the lesion as a common nevus. For some with liberal criteria for the diagnosis of Spitz nevus, the fascicular qualities near the dermal-epidermal interface and the spindle configuration of the melanocytic cells of the fascicles might lead to a diagnosis of “Spitz nevus” (Spitz melanocytoma) - (“next case” or “steam on, son.”)

P3-3: The lentiginous and junctional component away from the main dermal component is represented. By degree of atypia, this component qualifies as moderate dysplasia but the lesion is not acceptable as a marker for the dysplastic nevus syndrome. Markers for host immune response are too insignificant to suggest that this is a marker for the dysplastic nevus syndrome. This is a moderate melanocytic dysplasia of INDETERMINATE TYPE.

P3-4: In this second field (another section in the same ribbon), the nests of cells near the dermal-epidermal interface are larger and the cells show moderate cytologic atypia. The fascicles of cells in this area are loosely spaced in the widened papillary dermis. Maturation is less prominent in this field (nuclear changes are fairly uniform from the superficial to the deep margin). Some of the nests extend into the upper portion of the reticular dermis among collagen bundles.Also in this field on the right hand side, band-like infiltrates of lymphocytes have been added to the patterns. The band-like lymphoid infiltrates provide a halo nevus-like quality.

Here, an observer, with a willingness to dismiss the lesion as a common nevus, might waver. On the other hand, if the champion of the diagnosis of Spitz nevus gets this far in his manipulation of the nosepiece and in his observation of real images, he is likely to mobilize the parcel of virtual images related to the diagnosis of “Spitz nevus” and then proceed to the next case - there would be sufficient correspondence of real images and his virtual images to lend confidence to a precipitous decision. And then what of the lymphoid infiltrates; are they to be merely dismissed as halo nevus phenomena and priority then assigned to the parcel having relevance for the diagnosis of Spitz nevus?

p3-5: The loose spacing of nests of cells in the widened papillary dermis is a vertical growth-like quality but depending on the whims of the observer is also a nevoid (organoid) quality. The cells in the nests are spindle shaped, delicately pigmented , and clustered to provide “epithelioid” qualities. A portion of the band-like infiltrate of lymphocytes is represented on the left and focally the infiltrates extend in the stroma among individual nests of melanocytic cells (a halo nevus-like quality). The nests that are truly isolated in the dermis and not attached to the epidermis are few in number; the number is insufficient to satisfy the guidelines proposed in the concept of minimal deviation melanoma for the identification of a vertical growth component (5-6 nests of atypical cells in two strata in the papillary dermis and associated with markers for host immune response).

If in “pattern analysis” an observer has found the lens producing a real image at this magnification, should he remain confident in his diagnosis of “Spitz nevus?” Should he perhaps not only linger awhile but might it be to his, and the patient’s, benefit to puzzle over the deviations in cytologic features; the ragged outlines of the fascicles; and the host immune response with halo nevus-like qualities? Might sufficient insecurities be engendered to prompt the observer to question the utility of pattern analysis that is not reinforced by other more careful observations, and  by probing of various parcels of virtual images? Might this be something other than “Spitz nevus with halo nevus reaction?” Should he then simply assign the lesion to the category of melanoma and ignore all the subtle hints that might at first have led him to open the parcels of either the common nevus or the Spitz nevus? The observer finally must address the problem of what the patterns in the dermis signify; they do not fully satisfy criteria for the recogniton of early variant or typical vertical growth as defined in the concept of minimal deviation melanoma. For the observer who subscribes to the concept of melanoma in situ, upper migration of atypical cells is not there in the epidermis as a guide to the easy and premature characterization of the lesion as a melanoma, regardless of the pattern in the dermis. The observer must seek other parcels and perhaps he has supplied himself with too few. He may not have the tools for the interpretation of the patterns and might then fall back on a hedge such as a diagnosis of “Spitz nevus/tumor” or the even less attractive alternative of “no diagnosis but melanoma cannot be excluded - recommend re-excision.”

P3-6: The junctional components are fascicular and the component cells are rather short, plump, delicately pigmented, spindle cells. They are loosely attached to their neighbors. There are scattered melanophages. Focally lymphoid infiltrates hug the fascicles of melanocytic cells. The cytologic features differ from those of classic Spitz nevus; in addition, there is cytologic atypia.

The cytologic features in P3-5 should be disturbing, if a favored option is an assignment of the lesion to the category of either common nevus or Spitz nevus. These cytologic features are relatively common in fully developed, metastasizing melanomas (“real melanomas” with vertical dimensions beyond the boundary of 1.5 mm (see WHITHERS1, 2, 3, & INDEX3).