THE FUNGI in the group known as the "dermatophytes" acquired the name because of their propensity for limiting their pathogenic activities to the skin; their inability to survive in any of the deeper tissues of the body usually has been accepted as well established. In fact, in all but a small percentage of instances their range is even narrower, so that terms such as "epidermatophytes" or "keratophytes" might have been considered equally appropriate; they luxuriate in the keratin portions of the epidermis, the hair and the nails; they thrive less well in the rete and do not ordinarily penetrate deeper than the basal cell layer.
There are, however, at least three exceptions to this rule, two of which are well recognized and commonly encountered, constituting the clinical entities known as kerion Celsi and its variants and the polymorphic allergic manifestations classified as "dermatophytids." The third is but poorly understood,