What is causing a 5-day sore lesion on her arm with no exposure history?

This 48-year-old female presented for evaluation of tender lesions on her left arm of 5 days duration. She denies any exposure history. She has been taking ibuprofen as needed for muscle pains or headache

What is responsible for her lesions?

A. Brown recluse spider bite.
B. Fixed drug eruoption to ibuprofen.
C. Lichenoid keratosis.
D. Folliculitis.
E. Herpes zoster.

(Answer and discussion on next page)Answer—Herpes zoster

This patient had herpes zoster, which is an atypical presentation. The lesions were in a dermatomal distribution with soreness in the dermatome. She was otherwise healthy and did respond to antivirals. It would be unusual for brown recluse spider bites to be multiple. Lichenoid keratosis is not vesicular. Initial fixed drug reactions should be a solitary lesion with repeated episodes, sometimes developing multiple lesions but not in a dermatomal distribution. Folliculis is not dermatomal and appears around a follicle.   ■