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MDMHALO

MDMLMM

NEVOIDMDM

MDMhalo, metastasizing

Near-neoplasia

General Index

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PICTORIAL 1

PICTORIAL 2

PICTORIAL 3

PICTORIAL 4

P2-1: Green arrows identify fascicles of pigmented, “common” (small) “nevus” cells in the dermal component. Yellow arrows identify less distinct fascicles of epithelioid (round) cells (the epithelioid cells of the dermal component of halo nevus-like variants). To the right, the fascicles of epithelioid cells are uniform in size and vertically oriented; the patterns, in  resembling those of a common nevus, provide an organoid or nevoid quality. On the other hand with other sets of virtual images, they  might also be compared to variant vertical growth-like patterns. To the left above the lymphoid infiltrates (blue arrows), fascicles are thin, tortuous, and intimately associated with lymphoid infiltrates (halo nevus-like phenomena). Cells in this area are both spindle shaped and round. Red arrows identify junctional nests of pigmented spindle cells.

P2-2: The pattern is halo nevus-like. Nests of “nevus-like” cells extend into the dermal infiltrate of lymphoid cells. Two types of nevus cells are represented. The green arrows identify nests of small, “common,” pigmented nevus cells. The yellow arrows identify nests of epithelioid, “nevus-like” cells. Some of the nests of small, pigmented nevus cells are outlined by sheaths of the epithelioid, “nevus-like” cells. The relationships in areas suggest the possibility that the epithelioid cells may be derived from the population of small, pigmented cells, and  that the interplay between small, pigmented cells and lymphoid cells may have a role in the transformation; the combination might be characterized as an interstitial (dermal)  form of near-neoplasia of halo nevus-like type. As an option, the epithelioid cells of the fascicles may be descendants of the pigmented spindle cells in junctional patterns. In either case, the epithelioid population is acceptable as a marker for a neoplastic transformation in a melanocytic hamartoma (i.e., nevus) or for the emergence of a neoplasm of a distinctive type in which minimally deviant neoplastic melanocytic cells provoke a cytolytic, cell-mediated immune reaction.

P2-3: In this field, nests of small, pigmented nevus cells are marked by green arrows. A sheath of the epithelioid, “nevus-like” cells defines the periphery of some of the nests of small, pigmented cells. The transition from fascicles of pigmented spindle cells at the dermal-epidermal interface to the fascicles of epithelioid “nevus-like” cells in the dermis is abrupt and not continuous. The zone of vascularized fibrous tissue at the deep margin of the lesion is represented at the bottom of the field; it forms a barrier.

P2-4: Green arrows point to the extremities of a junctional nests. In the central nest, the cells are loosely attached to their neighbors and there are lytic defects. The junctional nests are not clearly in continuity with the fascicles of epithelioid cells; the patterns are not clearly those of a primary configuration; the cellular component of the dermis cannot be identified as the product of accretive growth at the dermal-epidermal interface but this may be a random variation and on other sections, it might be possible to demonstrate continuity.. Centrally, lymphoid cells have collected in lytic defects among the fascicles of epithelioid cells. These defects are interpreted as the sites in which the halo nevus phenomena (lymphocyte-mediated cytolysis) has resulted in the lysis of small, pigmented nevus cells, the implication being that the epithelioid cells are representative of a higher (progressive) stage of neoplasia than the population of small nevus-like cells; they are more resistant to the effects of the halo nevus-like phenomena than are the small nevus-like cells.