S4C19P11PLVA



S4C19P11-1: This example of PLVA shows well developed lichenoid qualities; the lesion has both lichen planus-like qualities (hyperplasia of the superficial unit and defined lytic defects at the dermal-epidermal interface), and erythema multiforme-like qualities (clusters of necrotic keratinocytes above the basal layer). There are lytic defects in the epidermal domain; the basal unit is not clearly represented. At certain stages, lichenoid reactions of all types can lose much of their histologic specificity.

S4C19P11-2: The superficial unit of the epidermis shows scattered, rounded, necrotic (apoptotic) cells. In addition, the entire superficial unit shows partial, or complete, coagulation necrosis (loss of nuclear staining); cell outlines are preserved, but many of the cells in the superficial unit show lysis of their nuclei. There is extensive lysis of individual cells in the basal unit with lymphocytes and histiocytes in the defects. To the right, there is a cluster of extravasated red blood cells .


S4C19P11-3: In this example of PLVA, the epidermis is necrotic; there is an extensive area of lysis of the epidermis with prominent infiltrates of inflammatory cells in the defect. The keratin layer is intact. Necrotic epithelium forms an intermediate zone between the intraepithelial (mainly subcorneal) defect and another defect separating the necrotic epithelium from the basement membrane zone. To the left, the necrotic epithelium is in the process of sloughing; there is a sub-epidermal defect.

S4C19P11-4 (for orientation see S4C17P9-1): The perifollicular component has extended into, and eroded, the epithelium of this follicle (apparently a late catagen pattern). The histologic patterns are modified by the phase of the involved follicle. The patterns have lichenoid qualities, but are not lichen planus-like.

S4C19P11-5: The epidermal and dermal patterns are pityriasic; they satisfy the criteria for the diagnosis of a lichenoid lymphocytic vasculitis. The variations define pityriasic qualities. There are scattered, individual apoptotic cells in the epidermis. The basal unit is relatively well defined; it contains a rich interstitial infiltrate of lymphocytes and histiocytes. There is a parakeratotic cap. There are collections of red blood cells in the dermis near the dermal-epidermal interface. In addition to follicular involvement as seen in S4C19P11-4, the infiltrates involve sweat ducts. There is some degree of atypia in the epidermal infiltrates of lymphoid cells ( atypical pityriasis lichenoides [mild T cell dysplasia of indeterminate type]).

S4C19P11-6: This is another example of the necrotizing, lymphohistiocytic vasculitis which occasionally is encountered in the setting of PLVA. The endothelium is swollen. The wall of the vessel shows fibrinoid necrosis.

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