S8C21P8Vasculitis (PPP)

S8C21P8-1: In this lymphocytic vasculitis, the epidermis shows slight hyperkeratosis; a basal unit is represented. The papillary dermis is thin and slightly edematous. There are perivenular infiltrates of lymphocytes and histiocytes. In addition, extravasated red blood cells are present in the papillary dermis and among basal keratinocytes. The basic requisites for the diagnosis of a lymphocytic vasculitis are satisfied. The infiltrates are relatively confined to perivascular spaces of the reticular dermis; there is evidence of vascular damage (extravasated rbc’s); and the epidermis is relatively normal. This combination of features is characteristic of a vasculitis; this pattern is common in the setting of a drug eruption.

S8C21P8-2: In this example of lymphocytic vasculitis, the epidermis is relatively uninvolved. The papillary dermis is widened and edematous (a vasculitic quality). The reticular dermis shows edema (collagen bundles are compressed; they are small in diameter and spaces among the bundles are widened). There are perivenular infiltrates of lymphoid cells with scattered eosinophils. The reticular dermis shows activation of mesenchyme cells and loose infiltrates of inflammatory cells, including eosinophils (lymphocytic vasculitis with eosinophilia; drug eruption is a good possibility).

S8C21P8-3: The basic patterns of a lymphocytic vasculitis is represented but, in this example, there is a small area of spongiosis in the epidermis; there are a few lymphoid cells in the area of epidermal edema. The papillary dermis is widened and edematous, but relatively free of inflammatory infiltrates. The reticular dermis shows a reduction in the diameter of collagen bundles, a feature in keeping with dermal edema. Perivenular infiltrates of lymphoid cells extend along vessels to at least the mid-portion of the dermis. There is a mild activation of connective tissue cells with spotty, loose, interstitial infiltrates of inflammatory cells. This pattern overlaps with the patterns of some of the lymphocytic infiltrates of the dermis; it is a pattern of cellular immunity. The appropriate label is a matter of opinion. The patterns share basic features with many examples of leukocytoclastic angiitides, differing mainly in the character of the reacting cell. Quite likely, this is a response to an antigen that is fixed in the interstitium of the reticular dermis. Quite likely, the interstitial matrix is a favorable site for the deposition of antigens. The vessel, itself, is as little, or as much, involved as are the vessels in many examples of “leukocytoclastic vasculitis.”

S8C21P8-4: Another form of lymphocytic vasculitis is the “lymphocytic capillaritis” of the progressive pigmented purpuras. In this field of such an example, there are perivascular infiltrates of lymphocytes, most prominent along the vascular plexus of the papillary dermis. There is also perivascular edema. There are vacuolar changes at the dermal-epidermal interface (a combination that might be characterized as a superficial lichenoid lymphocytic vasculitis). Lesions of this type tend to favor the lower extremities; they may be associated with extravasated red blood cells and hemosiderin deposits. Some examples may be disorders of the superficial reactive unit in which patterns are modified by the effects of increased intravascular pressure in the favored anatomic site.

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