S6C27P21-1: This subepidermal vesicle is cell-poor at the dermal-epidermal interface. To the right, the dermal papillae are effaced along the floor of the vesicle (this feature and the depression (concavity) along the floor of the bulla might be cited as evidence of tension in the bulla). To the left, the defect is loculated and there are scattered small areas in which the epidermis is attached to the dermis. The basal layer of the roof of the bulla is not represented on the far right. To the left, inflammatory cells form linear arrays along the floor of the defect. The defect contains a loose mesh of fibrin and a sprinkling of inflammatory cells. The dermis is edematous; it contains loose perivascular infitrates of inflammatory cells (dermatitis herpetiformis).

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S6C27P21-2: At this magnification, the loculations seen in S6C27P21-1 are supra-papillary defects with clusters of inflammatory cells along the surfaces of the flattened papillae. Some of the cells in the clusters are eosinophils (red arrows, with two in the defect to the right of the center of the field). The green arrows point to a region of the dermis that is more chromatic than the neighboring papillary dermis; in this area, the connective is smudgy and the nuclei (many of which have the nuclear configuration of migratory histiocytes) are pale (poorly stained); these staining qualities identify a zone of connective tissue that has been exposed to lytic and digestive enzymes; the cells are undergoing karyolysis.

S6C27P21-3: This is the classic, early defect at the dermal-epidermal interface in a lesion of dermatitis herpetiformis; the lesion is a supra-papillary abscess. The exudate in the supra-papillary defect has flattened the dermal papilla. The exudate of the compressed papilla has partially digested the infiltrated connective tissue. The exudate of the subepidermal defect is mostly neutrophilic, but a few eosinophils are admixed in the abscess. Eosinophils are also represented in the dermal infiltrates. To the right, green arrows identify an even earlier suprapapillary abscess. Yellow arrows point to eosinophils.

S6C27P21-4: In this field of a lesion of dermatitis herpetiformis, the infiltrates of neutrophils and histiocytes are diffuse at the dermal-epidermal interface; they are not sharply confined to the tips of dermal papillae. Blue arrows point to focal, lytic defects on the dermal side of the basement membrane (dermatitis herpetiformis).

S6C27P21-5 (DH): Blue arrows to the left identify an early suprapapillary abscess. To the right of this area, a dermal papilla contains extravasated red blood cells. The margin of the bulla is represented to the right; it is subepidermal, but there are also intrae-pidermal defects in reticulated patterns (thin bridges of flattened keratinocytes form the incomplete walls of the intraepidermal defects; athough this quality is not the foundation for the respective designation, the reticulated defects are an example of an “herpetiform” quality).

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