Erythema nodosum in patients with tinea pedis and onychomycosis

To document association between erythema nodosum and concomitant fungus infection, we studied seven white women seen during a six-year period in our office practice. Five patients are presented. Unilateral erythema nodosum occurred in three patients on the same side as unilateral tinea. Tests with potassium hydroxide (KOH), cultures of nodules on Sabouraud agar and dermatophyte test medium (DTM), skin biopsy, and clinical examination ruled out nodular granulomatous perifolliculitis of Wilson. Lesions simulating erythema nodosum were produced when Trichophyton antigen was injected subcutaneously in the lower legs. All nodose and fungal lesions cleared after griseofulvin therapy. Fungus infection of feet or nails should be considered a possible cause of erythema nodosum when no other cause is apparent.