S1C15P5-Perforations


S1C15P5-1: A follicle shows follicular occlusion; it is asymmetrical in outline. A column of hyperplastic squamous cells extends to the right into the dermis from the wall of the follicle (the extremity of the column is near the area containing green arrows). Inflammatory debris has collected in a cavity in the column. The adjacent dermis shows fibrosis with traceries of histiocytes among the collagen bundles (green arrows). The tinctorial quality of the cells forming the column is distinctive. The cells forming the column are larger than those of the adjacent follicular epithelium; in addition, they have pale cytoplasm. The cytoplasmic qualities are reminiscent of those of a keratoacanthoma; they are of a type commonly encountered in some forms of pseudoepitheliomatous hyperplasia (epithelial immunostimulation). The associations between inflammation, necrosis, and pseudoepitheliomatous hyperplasia are manifested.



S1C15P5-2: Often in the perforating disorders, the column of epithelial cells at the extremity of a perforation is open-ended, as in this field. In addition, the open end has a configuration that might be characterized as “claw-like.” Elastic fibers are preserved at the interface between viable and necrotic tissue; the fibers project into the defect. Green arrows identify keratinized lamellae in the exudate. The neighboring dermis contains interstitial infiltrates of neutrophils (red arrows).

	S1C15P5-3: Elastic fibers, in an exudate among collagen bundles, and just outside the area of necrosis, have taken on a bright acidophilia (fibrinoid change - blue arrows).

S1C15P5-4: The changes in the dermis, adjacent to an inflamed follicle, are clearly interstitial. Neutrophils and histiocytes have extended into the dermis among collagen bundles. There is edema of the dermis with widening of spaces among collagen bundles and with accentuation of the definition of the fibrils of the bundles. The neutrophic collagenosis may represent the initial change in perforating folliculitis; in this approach, the extension of epithelium into the dermis would follow a progression in the character of the reaction; it would follow progression of the inflammatory process to the stage of necrosis.

S1C15P5-5: To the right and below, the interstitial infiltrates are mild and similar to those of S1C15P5-4. To the left and above, the changes have progressed to necrosis. Necrotic keratinocytes (blue arrows) are present in the zone of necrosis at its extremity. Elastic fibers, that enter the zone of necrosis, have acquired a peripheral, bright, acidophilic sheen (red arrows).

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