What is Erythema Nodosum?
Erythema nodosum (EN) is a common skin condition that shows up as red, firm, and tender lumps or streaks, mostly on the front part of the legs. These bumps are known for their specific look under a microscope, no matter what caused them. They’re the result of intense inflammation at the layer where the skin and the fat tissue beneath it meet, and the areas between sections of the fat tissue. Importantly, they develop without leading to dying tissue or long-term changes.
Erythema nodosum is an intense or recurring response to different triggers and is more common in women. It can be linked to various triggers or illnesses. It’s crucial to recognize images of Erythema Nodosum to identify it correctly.
What Causes Erythema Nodosum?
Erythema nodosum is a condition that can happen due to a wide range of causes. Some of these include unknown origins, infections, and various non-infections related factors.
In about 30 to 50% of cases reported, there is no obvious cause which we call ‘idiopathic’.
In some instances, it’s due to infections. It could be any of the following:
Bacterial infections:
* Streptococcal infections, usually from a strep throat (seen in 28 to 48% of cases)
* Tuberculosis
* Leprosy
* Certain types of bacteria common in Europe, like Yersinia, salmonella, and campylobacter which can upset your stomach
* Bacteria that cause pneumonia, tularemia (rabbit fever) and cat scratch disease
* Other bacteria that can cause leptospirosis, brucellosis, psittacosis, and kinds of chlamydia
Viral infections:
* Mononucleosis, a common illness in adolescence caused by the Epstein–Barr virus (EBV), also simply known as ‘mono’
* Hepatitis B or Hepatitis C
* HIV
* Herpes simplex virus (HSV)
* Another type of Epstein-Barr virus
* Vaccinia, which is a relative of a smallpox family virus
Fungal infections:
* Fungal infections like Coccidioidomycosis, Histoplasmosis, and Blastomycosis
Parasitic infections:
* Parasites like Amebiasis and Giardiasis
Apart from infections, certain non-infectious reasons could be the cause:
Medications:
* Certain antibiotics like penicillins, sulfonamides
* Other drugs including oral contraceptives, iodides, bromides, and inhibitors of TNF-alpha (a protein involved in inflammation)
Cancer:
* Type of cancers including Leukemia and Lymphoma
* Hidden cancers that are not easy to detect
Inflammatory Bowel Disease:
* Crohn’s disease and Ulcerative colitis, types of chronic diseases that affect the gastrointestinal tract
Other causes:
* Sarcoidosis, a disease where immune cells form lumps and complications like Lofgren syndrome
* Pregnancy
* Other rare conditions including Whipple disease and Behcet disease
Some pregnant women may develop erythema nodosum during the second trimester. There is also a chance of this condition recurring with future pregnancies.
Risk Factors and Frequency for Erythema Nodosum
EN, also known as acute nodular hypodermis, is a condition that often appears as lumps under the skin. This condition usually occurs in women aged 25 to 40, although it can happen to anyone at any age. Women are three to six times more likely to have this condition compared to men. However, in children, both boys and girls are equally likely to have the condition.
- The condition is common and found all over the world.
- However, the rate at which people get it can vary based on their ethnicity or where they live.
- This is due to different triggers that cause the condition.
- In some cases, it can run in families. These instances are usually caused by an infection.
Signs and Symptoms of Erythema Nodosum
Erythema nodosum (EN) is a condition that follows a specific pattern, regardless of the cause. It has various phases:
Prodromal Phase:
- Usually lasts 3 to 6 days with nonspecific symptoms
- Often marked by fever, joint pain, and sometimes stomach pain
- Patients often have a upper respiratory infection with mild changes to their general well-being
Stade Phase:
- Begins quickly within 1 to 2 days
- Patients continue to experience fever and joint pain from the prodromal phase
- Nodules or bumps appear on the skin, especially areas such as legs, knees, thighs, and forearms
- The nodules are small, number between 3 to 6 or more, and are painful
- ON physical examination, these nodules are warm, firm, and cause pain when palpated
- Patients tend to lay down with their legs raised to relieve the pain caused by these nodules
- Swelling of the ankles is commonly seen
- Some patients might develop hilar adenopathy, a condition that can be confused with sarcoidosis
Regressive Phase:
- Nodules evolve over about ten days, ultimately disappearing without leaving any scars
- This phase can be enhanced by resting or receiving treatment
EN does not result in tissue death, ulceration or scarring, but it often occurs in several bursts, influenced by the patient’s posture. In the worst cases, these bursts can last for 4 to 8 weeks. The presence of nodules at different stages gives the eruption a varied appearance.
Besides the skin lesions, over half the patients also complain of pain in the joints and muscles. Some patients might experience joint swelling and stiffness, particularly in the mornings. The swelling might go away in a few days, but the pain could persist for several months. Usually, there is no joint destruction and the fluid within the joint is sterile.
Testing for Erythema Nodosum
If your doctor suspects you have the condition erythema nodosum (EN), it usually comes down to their examination since there’s often no need for extra tests in typical cases. Your doctor will need to know your complete medical history, meaning they may ask you about previous instances of tuberculosis, whether you’ve had a fever, instances of bloody diarrhea, abdominal pain, breathing problems, difficulty swallowing and so on, in an effort to isolate the cause of the condition (referred to as an ‘etiological diagnosis’).
However, depending on your symptoms, your doctor might need to run some tests to rule out other causes. These could include:
- A blood test to count your blood cells and determine your vital signs, or a C-reactive protein test if they think an infection might be causing your symptoms.
- A Mantoux test (a simple skin test to check for tuberculosis), a chest x-ray, and a blood test to measure the levels of a protein called interferon-gamma if tuberculosis or Löfgren’s syndrome (a form of sarcoidosis, a rare condition that causes small patches of swollen tissue to develop in the organs of the body) is suspected.
- A throat swab, bacterial culture, rapid test, and tests to check for anti-streptolysin O and streptodornase (an enzyme produced by certain streptococci) if they think the cause might be a streptococcal infection.
- Blood tests for viral infections, which might need to be repeated after four weeks, if they believe a virus might be to blame.
- Examination of your stool if you have diarrhea or any other digestive symptoms.
- A skin biopsy (removing a small piece of skin for examination) if your case isn’t typical or the diagnosis isn’t clear.
All these tests are designed to help your doctor figure out exactly what’s causing your symptoms, in order to give you the best treatment possible.
Treatment Options for Erythema Nodosum
If you’re experiencing pain, it’s recommended that you get plenty of rest – this may even mean taking some time off work. Pain relief medications will be given as requested. Compression of the veins can also help reduce the pain when you are standing.
Anti-inflammatory drugs known as steroids, along with a medication called colchicine, can be used until your symptoms get better. These are often administered at a dosage of 1 to 2 milligrams per day.
In certain cases, it will be crucial to treat the underlying condition causing your symptoms. For instance, if you have a streptococcal infection or tuberculosis, you’ll need to start antibiotics.
If you’re diagnosed with Löfgren syndrome – a specific type of sarcoidosis which involves fever, swollen lymph nodes in the chest, and joint pain – it’s recommended that your chest is monitored through regular X-ray checks. This is very important because while most people see their chest lymph nodes return to normal within a few months, in about 1 in 10 patients, the sarcoidosis may continue.
What else can Erythema Nodosum be?
An infectious skin condition known as non-suppurative infectious dermo hypodermitis needs to be diagnosed.
Nodular hypodermitis is a skin condition that affects the blood vessels and can lead to damage in the deeper veins. It can also affect the lower layers of skin, leading to the formation of nodules that can become necrotic, or tissue that dies off. To diagnose it, doctors primarily rely on information obtained from analyzing the affected tissue under a microscope.
Lobular hypodermitis, or panniculitis, involves lesions that are primarily oily or greasy. Like nodular hypodermitis, it is also primarily diagnosed through a histological examination—or looking at the cells and tissue under a microscope—of a biopsy, a small sample taken from the affected area. Several different types of this condition have been identified. The skin bumps or nodules that occur with this condition can break down, open up, and leave a scar.
What to expect with Erythema Nodosum
The outlook for patients with Erythema Nodosum (EN), a type of skin inflammation, is generally favorable, but there’s a small chance it could come back. The skin problems associated with EN usually take a few months to completely heal. However, the good news is that usually, no scars or changes in skin color are left behind once the skin has healed.
