Case 2: What caused this itchy patch on a girl's arm?

March 3, 2009

A 10-year-old girl with seasonal allergies has had this pruritic patch on her arm for a few days. She denies any exposure history.

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A 10-year-old girl with seasonal allergies has had this pruritic patch on her arm for a few days. She denies any exposure history.

Which of the following would you include in the differential?

A. Impetigo.B. Eczema.C.Herpes simplex.D. Contact dermatitis.E. Factitial dermatitis.

(Answer on next page.)

Answer: B. Eczema.

An eczematous patch, B, developed in this child with atopy as a result of colder weather and the patient’s bathing habits. She was advised to take shorter, cooler baths; avoid the use of a washcloth, poof, or loofah; avoid washing the rash; and pat dry and moisturize with a cream rather than a lotion immediately after her bath. By changing her bathing habits and applying a mild topical corticosteroid cream, she was able to control the ras

The other conditions in the differential mimic this condition, and cultures may be required to rule them out. Sometimes a therapeutic trial of an antibiotic will help determine the cause.