This 51-year-old woman presented with a 2-year history of chronic hand eczema that would partially respond to topical corticosteroids, only to recur. She denied any new exposure history. She had not had the condition in the past.

What explains this recurrent rash?
    A. Contact dermatitis
    B. Atopic dermatitis
    C. Psoriasis
    D. Lichen planus
    E. Dyshidrosis

What diagnostic measure could provide an important clue?
    A. Patch testing
    B. Examination of the fingernails
    C. Examination of the elbows and knees
    D. Examination of the feet
    E. Potassium hydroxide (KOH) preparation