Each nodule tends to last for approximately two weeks but new nodules
can continue to appear for up to six weeks. When the nodule first
appears it is usually red and firm to the touch. It then becomes more
fluctuant (squashy). As the nodule begins to fade, it looks more like a
bruise, turning blue and then yellowish. It takes one to two months for
the nodules to heal completely. They do not leave any scarring.
Other symptoms
Before the nodules appear,
most people tend to have a period of between one and three weeks where
they feel generally unwell. You may have a fever, a cough, lose weight,
have aching joints, stiffness and general aches and pains. Your joints
may be 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.
Symptoms from 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.
People with inflammatory bowel disease may have abdominal pain and
diarrhoea. People with tuberculosis may have a cough and breathing
problems.
How is erythema nodosum diagnosed?
Your
doctor can usually diagnose erythema nodosum by looking at it due to
its characteristic appearance. Sometimes, doctors may be uncertain that
a rash is erythema nodosum and they may perform a biopsy, taking a
sample of tissue from one of the nodules. The tissue sample can then be
examined underneath a microscope and the diagnosis can be confirmed.
Investigations to look for any underlying trigger
Usually, tests are then carried out to look for any underlying trigger for the erythema nodosum. These may include:
-
Blood tests. Your doctor may suggest some blood tests to look for signs of inflammation.
-
Tests for streptococcal infection. If your doctor suspects
that a streptococcal infection was the trigger, they may take a swab
from your throat to look for this. The swab is then sent to the
laboratory to see if infection is present. Some special blood tests can
also show if you have had a recent streptococcal infection.
-
Chest X-ray. If your doctor suspects that you may have tuberculosis or sarcoidosis, they may suggest that you have a chest X-ray.
-
Other investigations for tuberculosis. Your doctor may
suggest a special skin test, called a tuberculin skin test, or a
Mantoux test. These tests involve small injections into your arm and
are used to see if you have tuberculosis. If you have a cough, your
doctor may suggest that a sample of your sputum is sent to the
laboratory to look for TB infection.
-
Other investigations for sarcoidosis. If your doctor
suspects that you may have sarcoidosis, they may refer you to a lung
specialist for further investigations. These can include respiratory
function tests (special tests that look at your breathing). They can
also include CT and MRI scans of your lungs and a bronchoscopy (a
special camera that is inserted through your nose and mouth to look at
your airways and lungs).
-
Stool (faeces) specimens. These can detect infections such
as Salmonella and Campylobacter that may be triggers for erythema
nodosum. Your doctor may suggest these tests if you have erythema
nodosum and diarrhoea or abdominal pain.
-
Bowel investigations. If your doctor suspects that you may
have underlying inflammatory bowel disease such as ulcerative colitis
or Crohn's disease, they may suggest that you have investigations to
confirm this. These include investigations such as a colonoscopy (an
examination of your bowel with a camera).
What is the treatment for erythema nodosum?
Treatment for the nodules of erythema nodosum
The
nodules of erythema nodosum tend to go away by themselves and often do
not need any specific treatment. Specific treatments that may be used
include:
-
Painkillers. As the nodules can be very
painful, painkillers may be needed. Nonsteroidal anti-inflammatory
drugs (NSAIDs) are commonly used. Sometimes stronger painkillers are
needed. See separate leaflet on 'Anti-inflammatory Painkillers' for more details.
-
Bed rest, elevation of the legs and cool wet compresses. These measures may also be helpful to relieve pain in the nodules.
-
Iodine solutions. In some people with erythema nodosum, an
iodine solution taken as a liquid by mouth may help relieve the pain in
the nodules and also the joint pains. It is not certain how exactly
this works and it is not effective in everyone.
-
Steroid treatment. Steroids taken by mouth are sometimes
used to treat erythema nodosum provided that there is no infection or
cancer that has acted as a trigger. However, most of the time steroid
treatment is not needed.
Treatment of any underlying trigger
If an underlying trigger for erythema nodosum has been found, this may need to be treated. The treatment depends on the trigger.
What is the prognosis (outlook) for erythema nodosum?
Most
people with erythema nodosum tend to have healing of the nodules, with
no scarring, within seven to eight weeks. However, in some people with
idiopathic (unknown cause) erythema nodosum, it may last for up to six
months. Chronic (persistent) or recurrent erythema nodosum can occur
but it is rare. Generally, the outlook for erythema nodosum is very
good and most people do not have further problems.
If erythema
nodosum is the first sign of an underlying problem such as inflammatory
bowel disease or sarcoidosis, then the outlook for that particular
condition should be considered.
References
Disclaimer: This article is for information only and should not
be used for the diagnosis or treatment of medical conditions. EMIS and
PiP have used all reasonable care in compiling the information but make
no warranty as to its accuracy. Consult a doctor or other health care
professional for diagnosis and treatment of medical conditions.
© EMIS and PiP 2008 Updated: 23 May 2008
