S4C18P10-1: The orientation of keratinocytes, in which most of the cells in this field have their long axis perpendicular to the surface of the skin, qualifies the epidermal pattern as a form of basal unit hyperplasia. The faint lavender hue of the cytoplasm of keratinocytes in the basal unit might be cited as evidence of regenerative activity. Lymphoid infiltrates are diffuse among keratinocytes of the basal unit. Occasional necrotic keratinocytes with a pyknotic nucleus might be cited as markers for apoptosis (in the concept of apoptosis, death of individual keratinocytes, presumably, is programmed).

S4C18P10-2: In the mid to late ‘60’s, PLVA was promoted as a vasculitic process. Presumably, much of the histology, as represented in the reactive superficial unit, was to be accounted for on the basis of the effects of a vasculitis. I suppose there has been less emphasis on a vascular nature following the almost universal rejection of “lymphocytic vasculitis” as a real process. There are examples of PLVA in which the findings are clearly those of a necrotizing vasculitis. In this example, the vasculitis clearly is not a neutrophilic variant. In the area of fibrinoid necrosis, the cells identified by arrows are migratory histiocytes, not neutrophils. The pattern in this field qualifies as a necrotizing, lymphohistiocytic vasculitis with a high component of migratory histiocytes.

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