S11C13P8-Spirochetes

S11C13P8-1a & b: In this general study of the histologic features of basic reaction patterns, those, in these two figures, are both lichenoid, and vasculitic. The band-like infiltrates which hug and erode the basal layer of the epidermis contribute a lichenoid aspect to the lesion. The contribution, at this magnification, is to the general aspect; other features, at a higher magnification, must be identified to establish the true lichenoid character of the patterns. The definitive features, that would be required for the characterization of a reaction as lichenoid, would be the presence in the epidermal domain of evidence of lysis and coagulation of keratinocytes, all mediated at a cellular level by lymphocytes and histiocytes). The perivenular infiltrates of the reticular dermis contribute a vasculitic aspect. In combination, the reaction pattern is a lichenoid/lymphocytic vasculitis. These two features, when combined, constitute the common pattern of a variety of diseases. As an example, they are characteristic features of lesions of secondary lues. The patterns should alert the observer for the need to then search for histiocytes  and plasma cells, the two distinguishing cellular components of the inflammatory infiltrates of lues.

S11C13P8-2: Clearly, the reaction at the dermal-epidermal interface has lichenoid qualities. The rete ridges are effaced. There are vacuolar changes at the dermal-epidermal interface. The band-like infiltrates of the papillary dermis hug the epidermis. In contrast to lichen planus, there are prominent perivenular components in the reticular dermis.

S11C13P8-3: Stages in the evolution of a lichenoid reaction are represented. On the right, the blue arrows define the boundary between the superficial  and the basal units of the epidermis. Keratinocytes of the basal unit are loosely spaced (inter-cellular edema); they are smaller than the plump keratinocytes of the hypertrophied superficial unit (large, pale keratinocytes whose long axes are parallel to the surface of the skin). Lymphocytes  and histiocytes have collected in the small defects among the basal keratinocytes in the area beneath the blue arrows. The histiocytes are migratory forms; they appear as elongated, wavy, naked nuclei among keratinocytes and lymphocytes. There are small lytic defects in the basal layer in this area. The yellow arrows identify reduplicated basement membranes, another lichenoid feature. An occasional plasma cell is present among the reduplicated membranes. To the left of the center of the field in the region of the dermal-epidermal interface, there is no recognizable remnant of the basal unit of the epidermis. The absence of a marker for this unit identifies the cytolytic process, in this region, as a established phase (i.e., the patterns in the lytic areas are lichen planus-like). At the far left of the field, reduplicated basement membrane material  and fibrin are represented in abundant and complex patterns.

S11C13P8-4: Epithelioid granulomas are occasionally a feature of the reactions in secondary lues. The presence of granulomas does not necessarily equate with a tertiary stage of lues.

S11C13P8-5: In this lesion of secondary lues, red arrows identify plasma cells and blue arrows identify migratory histiocytes. Activated histiocytes, also represented in this field, have more abundant, pale, amphophilic cytoplasm, and delicate nuclear chromatin; some of the nuclei of activated histiocytes are notched, or reniform.

S11C13P8-6: With a Warthin-Starry stain, delicate spirochetes are demonstrated in the epidermis (blue arrows). If a demonstration of organisms, in this manner, were to be cited as a firm requisite for the histologic diagnosis of lues, many cases would go undiagnosed. The results with a silver stain are capricious. In addition, care is required in the fixation of the tissue.

 

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