History:

Tinea pedis with dermatophytide 

A 13-y-o girl suffered an itchy rash on both feet of 3 months duration.  A general practitioner prescribed superpotent topical steroid on an assumed diagnosis of foot eczema. Good improvement noticed within 2 weeks but one week later the rash flared up although the patient was still on treatment. With the flare up a vesicular rash appeared on both hands and feet. On examination, there were red scaly plaques on the dorsa of both feet. However, the web spaces between the toes were not affected. In addition numerous vesicles were seen on both hands and feet. Some vesicles had an iris or target appearance. Other body sites and mucous membranes were free of any lesion. KOH preparation of lesional scales yielded positive result for fungi. The patient was treated with an oral griseofulvin for 6 weeks with complete resolution of the condition.

The term 'ide' or 'id' denotes a reaction occurring in a part remote from the primary lesion, usually but not invariably due to an immunological reaction to the agent concerned or to its component parts, e.g. tuberculide, syphilide, trichophytide, eczematid. Id reaction may take many morphological patterns; most commonly a pompholyx-like picture and also erythema multiforme-like picture. Dermatophytosis may be complicated by an id reaction especially active cases of kerion, tinea cruris and tinea pedis.