Erythema Nodosum:
A Sign of Systemic Disease
ROBERT A. SCHWARTZ, M.D., M.P.H., and STEPHEN J. NERVI, M.D., University of Medicine and Dentistry
of New Jersey–New Jersey Medical School, Newark, New Jersey
E
rythema nodosum is a type of pan-
niculitis that affects subcutaneous
fat in the skin, usually first evident
as an outcropping of erythematous
nodules that are highly sensitive to touch.1
Most nodules are located symmetrically on
the ventral aspect of the lower extremities.
Although erythema nodosum usually has
no specific documented cause, it is impera-
tive to investigate possible triggers. Strep-
tococcal infections are the most common
identifiable etiology, especially in children.
Drug and hormonal reactions, inflammatory
bowel disease, and sarcoidosis are other com-
mon causes among adults.1,2 Often, erythema
nodosum is a sign of a serious disorder that
potentially is treatable; management of an
underlying etiology is the most definitive
means of alleviating erythema nodosum.
Overall, erythema nodosum occurs in
approximately one to five per 100,000 per-
sons. In adults, it is more common among
women, with a male-to-female ratio of 1:6.3,4
In children, the sex ratio is 1:1.2 Peak inci-
dence occurs in persons between 20 and
30 years of age, although erythema nodo-
sum can occur at any age.
Clinical Manifestations
Erythema nodosum nodules vary from 0.4 to
4 inches (1 to 10 cm) in diameter and are
poorly demarcated, reflecting their subcutane-
ous anatomic location (Table 11-4 ; Figure 1).
Pretibial involvement is most common,
although the extensor surfaces of the forearm,
the thighs, and the trunk also may be affected.
Initially, erythema nodosum nodules can be
firm, but they usually become more fluctuant
Erythema nodosum, a painful disorder of the subcutaneous fat, is the most common type of panniculitis. Generally, it
is idiopathic, although the most common identifiable cause is streptococcal pharyngitis. Erythema nodosum may be
the first sign of a systemic disease such as