Lues (introduction)

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 MICROSCOPIC FIGURES 1-3

 Ed. note: Because of the number and size of the figures and legends, these will be in small groups. Click on the appropriate underlined blue text at the bottom of the page to go to the next set of figures.

 

 


 

Fig. 1: Prominent perivascular infiltrates of lymphoid cells are present in the dermis. They are band-like at the dermal-epidermal interface. The infiltrates obscure the interface. This type of reaction qualifies as a cell-rich lichenoid lymphocytic vasculitis. The qualification of the reaction as cell-rich gives recognition to the character of the lichenoid reaction at the dermal-epidermal interface. The cell-rich category includes such diverse processes as the pityriasic disorders, the lichen planus-like disorders, and the erythema multiforme-like disorders. The qualification of the reaction as a variant of a lymphocytic vasculitis gives recognition to the distribution of the infiltrates in the reticular dermis.


 
 

Fig. 2: The dermal infiltrates are dense and focally micronodular. The infiltrates are dense at the dermal-epidermal interface. The keratin layer is little altered.


 

Fig. 3: The viewer is asked to view the patterns from right to left. On the left, the basal unit is outlined below the basement membrane by orange arrows and at the interface between the superficial and basal functioning units of the epidermis by blue arrows. Lymphocytes and histiocytes intermingle among keratinocytes of the basal unit. The pattern is that of a pre-lytic, lichenoid reaction and is of a type seen in the pityriasic disorders, particularly the pityriasis lichenoid-like disorders. The cells intimately intermingle among the keratinocytes of the basal unit and are not confined to the basal layer of cells. The orange arrows also identify the basement membrane. It is coarsened, more brightly acidophilic and focally duplicated. Centrally at the dermal-epidermal interface, there is a lytic defect containing lymphocytes and histiocytes. The basement membrane is interrupted in this area. This type of defect is likely to heal by an inlay of fibrous tissue in the defect and by the formation of a new basement membrane along the surface of the fibrous inlay. On the left, the pattern is that of an established lichenoid reaction. It is evidence of a common pathway in which more specific disorders lose their identity in the general category of “lichenoid” reaction. There is only a basal layer (no functioning unit) and the epidermis mostly shows the pattern of a hyperplastic and hypertrophic superficial functioning unit. The basement membrane is irregularly thickened and duplicated in this area. The tail of the top orange arrow is near a plasma cell in the infiltrates. Plasma cells are not a feature of pityriasis lichenoides.

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