S1C22P12Interfaces


S1C22P12-1: It would seem that the lichenoid reaction should be a rather general response in which distinctions among different disorders would be difficult to define. One might expect that lymphocytes and histiocytes would react in a limited fashion across a broad range of clinical disorders. The recognition of variants relates in part to the epidermal response and, for some variants, to the relative amounts of immunoglobulins deposited at the dermal-epidermal interface. In the pityriasic disorders, some leeway for variations in lichenoid patterns is provided by the degree of hyperplasia of the basal unit of the epidermis. This unit might be characterized as lymphocyte friendly ; its avenues are open and mucinous, particularly in inflammation processes; they allow inflammatory cells free access to the epidermal interstitium. In this field, especially to the left of the center of the field, lymphocytes are stratified in a basal unit that is only minimally hyperplastic, but clearly represented. The reaction at the dermal-epidermal interface is more cellular than is that of the usual example of lupus erythematosus; the infiltrates are both perivascular and band-like. There is extravasation of red blood cells into both the epidermis and the papillary dermis. The patterns along the vessels provide a vasculitic quality (pityriasis lichenoides et varioliformis acuta).



	S1C22P12-2: In this example of pityriasis lichenoides et varioliformis acuta, a damaged, but preserved, basal unit provides a domain that is accessible to migrating lymphocytes and histiocytes. The superficial unit of the epidermis (that superficial portion in which keratinocytes are elongated with their long axis parallel to the surface of the skin) is thin and poorly developed. The patterns are basically similar to those of S1C22P12-1.

S1C22P12-3: On the right, the epidermis shows a basal unit that is minimally involved by the lymphoid infiltrates. To the left, the epidermis is devoid of a basal unit; cells of the superficial unit are hypertrophied (the patterns have taken on a lichen planus-like quality). Vacuolar changes are prominent at the dermal-epidermal interface. Extravasated red blood cells are present in the epidermis and the dermis. The variable patterns encountered in lesions of the pityriasis lichenoides-like category are expressions of intervals, which taken together, define a life-history. The interface in the epidermis between the portion showing a basal unit and the portion showing a hyperplastic superficial unit is outlined by yellow arrows: the interface is so sharply defined it has “clonal” qualities.

S1C22P12-4: The patterns in lesions of secondary lues are variable and, again, the variations in large part are related to the age of the lesions selected for study. In this lesion, the patterns are vesicular, lichenoid and psoriasiform (pityriasic), and vasculitic (in combination, some of the features would qualify the lesion as a variant of a lichenoid lymphocytic vasculitis). The lesion is rather cell-rich at the dermal-epidermal interface. The perivenular infiltrates are dense and extend along vessels to the deep portion of the dermis. Infiltrates spill into the interstitium of the reticular dermis from the perivascular spaces (secondary lues).

S1C22P12-5: The patterns are spongiotic and mildly psoriasiform. In addition, there are vacuolar changes at the dermal-epidermal interface. Yellow arrows point to migratory histiocytes; they are numerous in the epidermis. Blue arrows identify the interface between a basal unit and a superficial unit of the epidermis. Plasma cells are not a prominent feature of the dermal infiltrates at this level (secondary lues ). The pattern is pityriasic.

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