S6C17P11-1: This is another example of a cell-poor subepidermal bulla in the clinical setting of bullous pemphigoid. The designation, cell-poor, gives recognition to patterns in the papillary dermis and near the dermal-epidermal interface. In contrast to other examples of bullous pemphigoid, as presented earlier in this numerical sequence, the infiltrates of the perivascular spaces in the upper portion of the reticular dermis are rather dense. In addition to lymphoid cells, they contain eosinophils and plasma cells. The infiltrates extend into the neighboring reticular dermis among collagen bundles (interstitial infiltrates). The lumen of the bulla is also cell-rich with a high component of eosinophils. In the setting of bullous pemphigoid, the clinical significance of this variation in the quantity and quality of the inflammatory infiltrates from patient to patient has not been defined.

S6C17P11-6: At a higher magnification at the margin of the bulla, the epidermis has separated from the papillary dermis; eosinophils and histiocytes have collected in the defect. Cells of the basal unit show cytopathic changes with cytoplasmic pallor and acidophilia; the cells of the basal unit, as represented over the defect, show degenerative changes with small, scattered intra-epidermal defects. The superficial unit is hyperplastic; it shows some degree of dyskeratosis. Focally, near the margin of the bulla, basal unit is partially preserved; the cells of the partially preserved basal unit are somewhat rounded in outline and have pale, acidophilic cytoplasm.

S6C17P11-7: In the dermis, the perivascular infiltrates contain plasma cells and eosinophils (bullous pemphigoid).