S13C13P11HaloNevusLike



S13C13P11-1: This is an example of a halo nevus-like lesion showing a well-developed area of regression with a heavy melanoderma. The epidermis shows spotty areas of liquefaction degeneration at the dermal-epidermal interface. Red arrows define an interface between a zone of papillary dermal fibrosis and the nodular zone of regression. There are no convincing markers for a population of nevus cells, or dysplastic melanocytes in this field. Clearly, this is a borderline pattern in which it is difficult to define the nature of the process.

S13C13P11-2: In this field of the same lesion as S13C13P11-1, the epidermis is thin; focally, rete patterns are effaced. There are perivascular and micronodular infiltrates of lymphoid cells with a high component of melanophages. The areas identified by blue (above the epidermis), and red (to right under dermal lymphoid infiltrates), arrows will be seen at higher magnification in the following two photomicrographs.

S13C13P11-3: This is a higher magnification of the area at the tip of the blue arrow in the preceding photomicrograph. In the area outlined by blue arrows, distinctive, epithelioid melanocytes are admixed among the histiocytes and lymphocytes. These epithelioid cells have an enlarged nucleus with dense chromatin patterns. These cells are cytologically of a type commonly encountered in the dermal component of halo nevus and halo nevus-like variants. They might be cited as a feature in support of the interpretation that the patterns of regression in S13C13P11-1 are part and parcel of a halo nevus. On the other hand, the possibility that the patterns of regression may be more significant and may be evidence of regression of a vertical growth component of a MDM of halo nevus-like type cannot be ruled out.

S13C13P11-4: Red arrows identify distinctive epithelioid cells of halo nevus-like type. I suspect some observers would characterize the lesion as Spitz nevus with halo nevus phenomena.

S13C13P11-5: This area corresponds to the area at the tip of a red arrow in S13C13P11-2. The green arrows identify a junctional component; the cells are spindle shaped and dendritic; they are loosely attached to their neighbors. In addition, they are pigmented. The cells of the junctional component show some variation in nuclear size and staining. Red arrows identify the characteristic epithelioid melanocytes commonly encountered in the dermal component of halo nevus and halo nevus-like variants.

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