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Great Ormond Street Hospital for Children NHS Foundation Trust: Information for Families
Erythema nodosum
This information sheet from Great Ormond Street
Hospital explains the causes, symptoms and treatment
of erythema nodosum and where to get help.
Erythema nodosum is a dermatological
(skin) condition. It is a type of
panniculitis. Panniculitis is the name
for inflammation of the layer of fat
lying underneath the skin. It causes
red nodules (rounded lumps) to form
just below the skin surface, usually on
the shins. In most people, there is no
obvious reason or cause for erythema
nodosum to occur.
and inside the throat. This is the most
common trigger for erythema nodosum in
children.
What causes
erythema nodosum?
There are also other infections which can
trigger this condition.
In most people, there is no obvious
reason or cause for erythema nodosum
to occur. Doctors call this idiopathic
erythema nodosum (as idiopathic means
of unknown cause).
However, in some people a trigger can
be identified. The most common trigger
for this skin condition is a streptococcal
infection or sarcoidosis. Streptococcal
infections are any type of infection caused
by a type of bacteria called streptococcus
or ‘strep’ for short.
Strep infections can vary in severity from
mild throat infections to pneumonia.
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Sarcoidosis is a disease of unknown cause
that leads to inflammation which causes
tiny lumps of cells to form in various
organs in the body, most commonly in
the lungs and lymph glands. The lumps
are called granulomas. Sarcoidosis is a
common trigger for erythema nodosum in
adults.
Tuberculosis (TB) can trigger erythema
nodosum. This is a bacterial infection that
usually affects the lungs.
Infections such as chlamydia (a disease
caused by bacteria which is most
commonly sexually transmitted),
mycoplasma pneumoniae (a type of
atypical pneumonia which can affect
younger people), yersinia enterocolitica (a
bacterial infection that causes diarrhoea
and abdominal pain), salmonella (a
foodborne illness caused by bacteria)
and campylobacter (another foodbourne
infection) are other, less common,
triggers.
There are more than 20 different types
of strep bacteria but one group is called
group A strep (strep A), which are
often found on the surface of the skin
A reaction to certain drugs may trigger
erythema nodosum in some people. For
example, reactions to some antibiotics or
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© GOSH NHS Foundation Trust April 2012
the combined oral contraceptive pill.
People with an inflammatory bowel
condition such as ulcerative colitis and
Crohn’s disease may also develop this
condition and pregnancy can also trigger
erythema nodosum.
Certain cancers including lymphoma and
leukaemia can also be triggers.
In cases where a trigger can be found,
it is thought that erythema nodosum is
caused by the immune system becoming
hypersensitive (or over-reacting) to the
trigger. Sometimes erythema nodosum
may be the first sign of the serious
underlying condition that needs to be
identified and treated. Erythema nodosum is rare. It affects
between two and three people in every
10,000 people per year in the UK. It is
most common between the ages of 20
and 35 but it can occur at any age.
What are the signs
and symptoms of
erythema nodosum?
Usually the first sign of erythema
nodosum is flu-like symptoms.
This happens before the nodules appear
and may a child feel generally unwell for
a few weeks. They may have a fever, a
cough and may lose weight during this
time.
They may also have aching joints, stiffness
and general aches and pains. Their joints
may become swollen. Ankle, knee and
wrist joints are most commonly affected
but any joint can be painful. Aching legs
and joints can last for a number of weeks,
or even months, after the nodules have
appeared.
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The nodules (rounded lumps) that occur in
erythema nodosum can measure between
two to six centimetres across. The shins
are the most common site. Other common
sites are on the arms, thighs and trunk but
nodules can occur anywhere on the body.
Each nodule tends to last for about two
weeks but new nodules can continue to
appear for up to six weeks. When the
nodule first appears it is usually red, hot
and firm to the touch. It then becomes
more squashy. As the nodule begins to
fade, it looks more like a bruise, turning
blue and then yellowish. It usually takes
some weeks for the nodules to heal
completely. They do not leave any scarring. Sometimes there can be symptoms due to
the underlying trigger.
These depend on the trigger. For example,
the nodules of erythema nodosum
can appear two to three weeks after a
streptococcal throat infection.
How is erythema nodosum
normally diagnosed?
If you suspect that a child has erythema
nodosum they should be taken to a GP.
A doctor will usually diagnose erythema
nodosum by its typical appearance. They
may also refer the child to a specialist for
a biopsy.
During a biopsy, a small sample of tissue is
taken from one of the nodules. The tissue
sample is then sent to the laboratory to
be examined under a microscope.
If the doctor diagnoses erythema
nodosum, they will usually suggest some
tests to look for an underlying trigger.
The tests that they suggest may depend
on any other symptoms that the child
may have. They may include blood tests,
© GOSH NHS Foundation Trust April 2012
a swab of their throat to see if infection
is present and/or a chest X-ray to look for
signs of TB or sarcoidosis.
The doctor may suggest a special test
called a tuberculin skin test. The test
involves having a small injection into the
child’s arm. It is used to see if they have
TB. If the child has a cough, the doctor
may suggest that a sample of sputum
(phlegm) be sent to the laboratory to look
for TB infection.
The child may be referred to a lung
specialist for further investigations.
Sometimes a doctor will need a stool
(poo) sample which can detect infections
such as salmonella and campylobacter.
Children who may have underlying
inflammatory bowel disease such as
ulcerative colitis or Crohn’s disease,
might need to have a colonoscopy (an
examination of the bowel with a camera).
How is erythema nodosum
normally treated?
The nodules of erythema nodosum tend to
go away by themselves and often do not
need any treatment. However if they are
tender or painful treatments may include:
pain in the nodules and also the joint
pains.
„„Steroids – which are sometimes used
provided erythema nodosum is not
thought to have been triggered by an
infection or a cancer. They work by
reducing inflammation.
If an underlying trigger for erythema
nodosum has been found, this may need
to be treated. The treatment depends on
the trigger.
What next
For most children with erythema
nodosum the nodules tend to heal, with
no scarring, within six to eight weeks. In
some children with idiopathic erythema
nodosum, nodules may last for up to
six months or more. Most do not have
further problems.
Chronic (persistent) or recurrent erythema
nodosum can occur in some children but
this is rare.
Notes
„„Painkiller medication.
„„Bedrest
„„Wearing firm, supportive bandages or
stockings on your legs.
„„Using cool wet compresses over the
nodules
„„Taking potassium iodide – liquid taken
by mouth which may help relieve the
Compiled by the GOSH web team
Great Ormond Street Hospital for Children NHS Foundation Trust, Great Ormond Street, London WC1N 3JH
www.gosh.nhs.uk
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© GOSH NHS Foundation Trust April 2012