S7C5aP2a-Linear IgA Dermatitis

S7C5aP2a-1: The separation at the dermal-epidermal interface is diffuse.The underlying papillary dermis presents the pattern of a “cell-poor” interface reaction; the defect contains condensed fibrin and an infiltrate of neutrophils, histiocytes, and eosinophils. The basal layer of the epidermis focally is interrupted. The surviving basal keratinocytes (i.e., a single layer of basal cells) show degenerative changes with increased cytoplasmic acidophilia.

S7C5aP2a-2: This is representative of another biopsy specimen from the same patient (i.e., a specimen separate from the lesion represented in S7C5aP2a-1). The bulla is well-developed and subepidermal. It contains a mesh of fibrin and inflammatory cells. There are perivascular infiltrates of inflammatory cells in the upper portion of the dermis.The papillary dermis, away from the perivascular components, is cell-poor.

S7C5aP2a-3: The papillary dermis is cell-poor; it contains loose infiltrates of histiocytes with a sprinkling of neutrophils. The perivascular infiltrates are composed of lymphocytes and histiocytes with occasional neutrophils. Green arrows identify eosinophils in the dermal infiltrates among collagen bundles of the reticular dermis.

S7C5aP2a-4: Basement membrane is not readily apparent along the floor of the defect. The papillary dermis contains a loose infiltrate of migratory histiocytes with a sprinkling of lymphocytes, neutrophils, and eosinophils (green arrow).

S7C5aP2a-5: At low magnification, this lesion of linear IgA dermatitis shows a subepidermal bulla on the left. The keratin layer is relatively normal. To the right (blue arrows), infiltrates of histiocytes and neutrophils are arranged in linear arrays in the papillary dermis and at dermal-epidermal interface; dermal papillae and the relationship of the small defect (red arrow) to a dermal papilla cannot be defined.

S7C5aP2a-6: The margin of the subepidermal bulla is to the left. Linear infiltrates of histiocytes and neutrophils extend to the right from the region of the bulla.

S7C5aP2a-7: Histiocytes and neutrophils have collected in linear arrays at the dermal-epidermal interface. There are vacuolar changes in the region of the basement membrane.

 

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