pityriasis rosea

Why has this rash resisted topical antifungals?

DAVID L. KAPLAN, MD—Series Editor: Dr Kaplan is clinical assistant professor of dermatology at the University of Missouri Kansas City School of Medicine and at the University of Kansas School of Medicine. He practices adult and pediatric dermatology in Overland Park, Kan.

Volume 52 - Issue 10 - October 2012

 Pityriasis rosea

After 1 month of scratching this slightly pruritic rash on his trunk, a 12-year-old boy was referred for consultation. Another physician had prescribed topical terbinafine for a presumed fungal infection, but no improvement was noted.

What condition caused this eruption?

A. Pityriasis alba.

B. Pityriasis rosea.

C. Pityriasis lichenoides et varioliformis acuta (PLEVA).

D. Pityriasis amiantacea. 

E. Pityriasis (tinea) versicolor.

(Answer on next page)

 

 

Pityriasis rosea

Answer: Pityriasis rosea

A careful search of the patient’s skin revealed a herald patch—a large, solitary lesion that precedes the eruption of pityriasis rosea, B—on the boy’s shoulder. None of the other conditions in the differential feature a herald patch.

Pityriasis alba appears as a temporary, poorly defined area of hypopigmentation in atopic persons. PLEVA presents as crusted papules—not macules. Pityriasis amiantacea is confined to the scalp. A negative potassium hydroxide evaluation ruled out tinea versicolor.