F2Ch4 (106049): Scattered dyskeratotic cells are present in the epidermis; there is one necrotic keratinocyte. To the right side of the rete ridge, an acidophilic “basement membrane” is irregularly represented. The yellow arrows identify an area in which a basement membrane is poorly defined (a thin red line). Beneath this thin red boundary, there is a pale zone containing delicate fibrils.

F3Ch4 (106049): Rete patterns are effaced. Centrally, a thin basal unit is represented. There is hypergranulosis. The yellow arrow identifies a pale, swollen cell; this is interpreted as a keratinocyte on its way to “ballooning degeneration.” The basement membrane is irregularly coarsened; focally, the coarsened membrane is brightly acidophilic and refractile. An occasional basal cell has acidophilic cytoplasm. There scattered “apoptotic bodies.” There is intercellular edema among the basal keratinocytes. Focally, what appears to be basement membrane material forms a loop about a clear space that contains a small spindle cell (to the right of a blue arrow). There is a “adventitial domain” but no evidence of a normal papillary dermis.