Came across this useful snippet of knowledge today. A dermatophytide reaction is an allergic response to a fungal infection elsewhere in the body – according to one reference, it affects 4 – 5% of patients with tinea pedis, though I suspect this figure will turn out to come from secondary care. It may present as:
1. Desquamation of the palms, with no associated inflammation or itching (most common form)
or 2. itchy vesicles of palms, soles, or both, which may look indistinguishable from pompholyx eczema. (There are some complicated criteria for telling the difference, which I probably won’t need to know.)
Systemic steroid therapy may be needed for severe cases.