S11C19P14-3: The epidermal pattern is psoriasiform with hyperplasia of both the basal and the superficial units. The keratin layer shows compact orthokeratinization (PAS stain with green counterstain). Fungal hyphae are prominent in the keratin layer.

S11C19P14-4: The epidermis shows mild hyperplasia of the superficial unit with mild compact, hyper-orthokeratosis. The dermis and epidermis are relatively free of infiltrates of inflammatory cells. Arrows point to rounded spaces among keratinized lamellae; some of the spaces show a small, central, basophilic puncta. The rounded defects and the basophilic structures are representative of fungal hyphae cut in cross-section. Organisms, in a lesion such as this, are easily over-looked.

S11C19P14-5: The lumen of a follicle is represented. Chains of arthospores are present among keratinized lamellae. Green arrows identify organisms in ectothrix patterns. The structure in the center of the field (and the lumen of the follicle) is an altered hair shaft; red arrows point to organisms in endothrix patterns.

S11C19P14-6: The basic pattern is that of a spongiotic dermatitis with a hyperplastic basal unit showing inter-cellular edema. The superficial unit is also hyperplastic. There is a zone of parakeratosis with some evidence of “dyskeratosis.” In the fissured, altered keratinized debris above the zone of parakeratosis, there are scattered fungal organisms.

S11C19P14-7: At a higher magnification, green arrows identify fungal organisms in the keratin layer. Organisms often appear as empty defects among keratinized lamellae, but in some examples, as in this field, the organisms have an affinity for hematoxylin. The basal unit of the epidermis shows inter-cellular edema (spongiosis). The superficial unit is hyperplastic with a prominent granular layer.