S2C13aP7aPustularPsoriasis



S2C13aP7a-1: The defect in the epidermis is a ruptured pustule. In the adjacent superficial unit of the epidermis, the moth-eaten appearance is the result of lytic effects produced by enzymes released into the epidermal interstitium by degenerating neutrophils; the lesion is a spongioform pustule. The process, clinicopathologically, is impetigo herpetiformis.

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S2C13aP7a-2: The pustule is intra-epidermal and subcorneal. The exudate has been lost from the large defect to the left of the center of the field.

S2C13aP7a-3: The epidermis forming the roof of the main defect shows reticulated defects; the defects represent sites in which the enzymes released by neutrophils have partially digested the cytoplasm of dead keratinocytes. Remnants of partially keratinized cytoplasm form the walls of the small defects. The defects contain neutrophils.

S2C13aP7a-4: The patterns in the superficial unit of the epidermis are spongioform and pustular. The defects of the spongioform component are unusually large; they contain proteinaceous material and collections of neutrophils.

S2C13aP7a-5: The vessel (green arrows) of the dermal papilla is dilated (a psoriasiform quality); it shows margination of neutrophils, a feature of inflammation. This alteration in the capillary is the type of change that has been promoted in the concept of the “squirting papilla.”

S2C13aP7a-6: Reticulated defects among viable keratinocytes contain neutrophils; the patterns are spongioform.

S2C13aP7a-7: The patterns are those of a spongioform pustule (impetigo herpetiformis).

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