Erythema Multiforme
MICHELE R. LAMOREUX, M.D., MARNA R. STERNBACH, M.D.,
and W. TERESA HSU, M.D., PH.D., Drexel University College of Medicine, Philadelphia, Pennsylvania
E
rythema multiforme is an acute,
self-limited, and sometimes recur-
ring skin condition considered
to be a hypersensitivity reaction
associated with certain infections and med-
ications (Table 11,2).2,3 Previously, the con-
dition was thought to be part of a clinical
spectrum of disease that included erythema
minor, erythema major (often equated with
Stevens-Johnson syndrome [SJS]), and toxic
epidermal necrolysis (TEN), with erythema
minor being the most mild and TEN the
most severe.4 An often-cited study from
1993 proposed a useful clinical classification
of erythema multiforme, SJS, and TEN based
on the pattern of individual skin lesions and
the estimation of body surface area with
detachment of the epidermis (i.e., blisters,
denuded areas, or erosions) at the worst
stage of the disease (Table 21,2,5,6).5 Although
SJS and TEN may represent the same pro-
cess with differing severity,6 erythema multi-
forme, with its minimal mucous membrane
involvement and less than 10 percent epider-
mal detachment, now is accepted as a distinct
condition. The remainder of this article will
focus on erythema multiforme.
Etiology and Pathophysiology
Erythema multiforme usually occurs in adults
20 to 40 years of age,6 although it can occur
in patients of all ages.1 Herpes simplex virus
(HSV) is the most commonly identified etiol-
ogy of this hypersensitivity reaction, account-
ing for more than 50 percent of cases.1,3,7-10
Mycoplasma pneumoniae is another com-
monly reported etiology, especially in children,
as is fungal infection.1,11,12 The medications
most often associated with erythema multi-
forme are barbiturates, hydantoins, nonste-
roidal anti-inflammatory drugs, penicillins,
phenothiazines, and sulfonamides.2
In addition, there have been reports of ery-
thema multiforme associated with vaccines
Erythema multiforme is a sk