What is responsible for a two-day rash on his hands and arms?

This 57-year-old male presented with a two-day history of rash on his hands and arms after being treated with a sinus infection with doxycycline.

What could be responsible for the rash?

A. Photo drug reaction. 

B. Erythema multiforme.

C. Psoriasis.

D. Actinic keratosis.

E. Porphyria cutana tarda.

(Answer and discussion on next page)

ANSWER—Photo drug reaction

There are different types of photo drug reactions. The most common is phototoxic, which typically can onset within minutes and upto several hours on sun-exposed surfaces and appears as a sunburn. Photo allergic reactions require repeated exposure, have an onset timeframe of 1-2 days, can spread onto non-sun exposed areas, and appear rash-like. Lichenoid drug eruption (as seen in this patient) can be photodistributed. ■

David L. Kaplan, MD, 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, KS.