Although the capsule does not stain with hemotoxylin-eosin or the PAS reaction, the presence of acid mucopolysaccharides results in metachromatic purple staining with methylene blue, blue staining with alcian blue, and red staining with mucicarmine. When the spore develops a wide gelatinous capsule, inflammation is minimal leading to the so-called gelatinous reaction. Yeast cells do not form a capsule and usually elicit an intense granulomatous inflammatory reaction.
Description
Low power shows a pale well demarcated papule with attenuated overlying epidermis, multiple organisms and little inflammatory reaction. High power shows aggregates of spores with large capsules that do not stain with H&E resulting in large surrounding clear spaces.
