Page 98 - Journal of Special Operations Medicine - Fall 2014

An Ongoing Series

Erythema Multiforme

Charles A. Sola, MD; Trisha Clarke Beute, MD

ABSTRACT
An active duty male Soldier presents to your clinic with Figure 1 Clinical photograph of a lesion on the foot.
concerns of blister-like lesions on both hands and feet
several weeks after receiving immunizations. He is diag-
nosed with erythema multiforme (EM), a hypersensitiv-
ity reaction that is typically self-resolving. This article
reviews the etiologies, pathophysiology, course, diagno-
sis, and treatment of erythema multiforme.

Keywords: erythema multiforme, vaccines, smallpox, typhoid,
anthrax

Introduction
Skin lesions and rashes are common complaints in the
primary care setting. A thorough history and proper
identification of the morphologic characteristis of the
lesions can help to narrow the differential diagnosis or
identify the underlying disease. This article presents the What is the likely diagnosis? Is this an inoculation of
case of a skin lesion occurring after an immunization smallpox? How would you treat this disease?
and describes the underlying disease process.
The lesion shown in Figure 1 has a central crust with
surrounding edema and an outer ring of erythema. This
Case Presentation
lesion is referred to as an iris or targetoid lesion, and it is
A 20-year-old Soldier presents to the clinic for evalua- a classic finding in EM. The patient is reassured that the
tion of new-onset skin lesions. Approximately 2 weeks lesions are not caused by inoculation of smallpox, and
earlier, he noticed a blister-like lesion on his left middle he is given topical clobetasol 0.05% ointment to apply
finger. Two days later, he developed similar lesions on twice a day for up to 2 weeks.
his right hand and on both feet. The lesions are puritic,
but he denies any associated pain. He has been apply-
ing hydrocortisone cream daily, which temporarily helps Discussion
with the pruritis. He denies applying any other medi- Erythema multiforme is an acute dermatologic syndrome
cations, including over-the-counter drugs. He denies that can affect patients of all ages but is commonly seen
having any lesions in his eyes or mouth, and none are in young adults aged 20 to 40 years. The pathogen-
1,2
present on examination. Five weeks ago, he was vac- esis of EM is believed to be a result of a delayed type
2
cinated for typhoid, anthrax, and smallpox. The small- of hypersensitivity reaction. This is a T-cell–mediated
pox vaccination site is completely healed at the time process resulting in an inflammatory cascade. It was
1,3
of examination. Figure 1 is a photograph of one of the previously thought that EM was a mild form of a spec-
patient’s lesions. How would you describe this lesion? trum of disorders, including Steven-Johnson syndrome

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