Why has this eczema resisted topical corticosteroids?

A 56-year-old man has had eczema only on his dominant, right hand for 30 years. He had tried topical corticosteroids, but they failed to clear the condition.

Which of the following is your initial diagnostic approach?

A. Examination of the feet.

B. Potassium hydroxide (KOH) evaluation.

C. Patch test for contact dermatitis.

D. Examination of the nail plate.

(Answer on next page)

Answer: Tinea manus

A KOH evaluation, B, will confirm the diagnosis of a dermatophyte infection, tinea manus. When an id reaction to a dermatophyte is suspected, examination of the patient’s feet is appropriate. A patch test is called for in patients who have eruptions without obvious contactants and who have not responded to therapy for a presumed diagnosis. A nail plate examination may reveal evidence of psoriasis, which can be exacerbated by trauma.

The extensive involvement of this patient’s eczema warrants systemic as well as topical antifungal treatment. Two weeks of this regimen restored the hand to its normal appearance, which the patient had not seen for 30 years.