What do you suspect is causing her 3-month rash and how would you treat the patient?

A 50-year-old female presented for evaluation of rash of 3 months duration on her trunk and upper arms that had failed topical treatment. She sleeps with the dog in her bed and the dog had been diagnosed with ringworm. The dog has been treated, but the patient failed to get better with topical naftifine and clotrimazole creams. The rash is mildly itchy. She is otherwise healthy.

What do you suspect is the cause and how would you treat the patient?

A. Treatment failure of dermatophyte infection requires systemic treatment with terbinafine

B. Recommend ketoconazole shampoo as body wash daily

C. Suspect patient is overbathing and should start moisturizing

D. Asteatotic eczema requiring moisturizers and topical steroid cream

E. Pityriasis rosea that looks like ringworm and will respond to topical steroid cream

(Answer and discussion on next page)

Answer: Pityriasis rosea

This patient had pityriasis rosea and a preceding upper respiratory illness. This condition often mimics ringworm. Extensive ringworm will often require systemic treatment but should demonstrate a positive culture or chemical potassium hydroxine (KOH) exam.