Tinea Pedis and Reactive Eruptions

A 42-year-old woman had had athlete's foot for years, but the condition suddenly worsened when inflamed, pruritic vesicles appeared on both feet (A). A few days later, tiny, mildly itchy vesicles erupted on her palms (B); the rest of the hands were not involved. One week after the palmar eruptions, the patient noted 2 round, reddish brown, asymptomatic 3-cm macules on her trunk (C). These lesions had faint scaling on the trailing edge of the slowly advancing arciform borders.

Joe Monroe, PA-C, of Tulsa, Okla, suspected that the 3 types of eruptions were related. A potassium hydroxide (KOH) evaluation of a blister roof confirmed the diagnosis of tinea pedis, or athlete's foot, on both feet. The palmar eruption was a response to the fungal antigen, or an id reaction. The differential diagnosis for both the foot and hand lesions included contact dermatitis and dyshidrosis.

The differential diagnosis of the truncal macules included nummular eczema, tinea corporis, psoriasis, and erythema annulare centrifugum. The morphology of the eruption-trailing scale and arciform-bordered macules-the negative KOH examination, and the timing of the condition's appearance and resolution are characteristic of the reactive erythema, erythema annulare centrifugum.

The tinea pedis was treated with oral and topical terbinafine; the foot lesions resolved, followed by those on the hands and the trunk.