Erythema Nodosum

Erythema nodosum is a skin condition that causes tender, red, and warm lumps (nodules) to appear, usually on your shins. These lumps are a sign of inflammation in the fat layer just under your skin. While often painful, erythema nodosum is usually not serious and typically resolves on its own within a few weeks.

What is Erythema Nodosum?

Erythema nodosum is a type of inflammation affecting the fat cells just beneath your skin, leading to the formation of tender, red, and warm lumps (nodules). These lumps most commonly appear on the front of your lower legs, specifically your shins, but can also occur on other areas like your thighs, arms, or trunk.

This condition is considered a form of panniculitis, which means inflammation of the fatty tissue under the skin. The lumps often start out bright red and firm, feeling painful to the touch. Over time, they may change color, similar to a bruise, turning purple, brown, or yellow before fading away. Erythema nodosum is usually a temporary condition. In most cases, the lumps resolve on their own within about three to six weeks. While the lumps typically disappear without leaving scars, the affected skin might show some temporary discoloration, like a bruise, for a while afterward.

Symptoms

The main symptom of erythema nodosum is the appearance of painful, red, and warm lumps (nodules) under the skin, most often on the shins. These lumps can range in size from about half an inch to two inches across.

Initially, the lumps are usually bright red and firm. They are often very tender and painful, especially when touched or when you walk. As the lumps heal, they typically change color, much like a bruise would, progressing from red to purple, then brown, and finally yellow before disappearing. Beyond the skin lumps, you might experience other general symptoms. These can include joint pain (arthralgia), which may affect your ankles, knees, or other joints. Some people also develop a fever, feel tired (fatigue), or have a general sense of feeling unwell (malaise). Swelling in the affected area around the lumps is also common.

Causes & risk factors

Erythema nodosum is often a reaction to an underlying condition, infection, or medication, rather than a disease itself. In many cases, however, no clear cause is found, and it is then called idiopathic. Common triggers include infections, inflammatory diseases, and certain drugs.

One of the most frequent causes is a strep throat infection (streptococcal infection). Other infections, such as tuberculosis, fungal infections, or mononucleosis, can also trigger erythema nodosum. Inflammatory conditions like sarcoidosis, an inflammatory disease that can affect various organs, and inflammatory bowel disease (Crohn's disease or ulcerative colitis) are also known causes. Certain medications can also lead to erythema nodosum. These include some sulfa drugs, penicillin, and oral contraceptives (birth control pills). Pregnancy is another known trigger for the condition in some women. While anyone can develop erythema nodosum, certain factors increase your risk. It is more common in young adults, typically between the ages of 20 and 30. Women are also more likely to develop erythema nodosum than men, with some sources suggesting they are three to six times more likely to be affected.

How it's diagnosed

Diagnosing erythema nodosum usually begins with a physical examination of your skin and a review of your medical history. Your doctor will look at the characteristic lumps and ask about any other symptoms you are experiencing. The goal is often to identify any underlying cause.

To help determine the cause, your doctor may order several tests. Blood tests are common and can check for signs of inflammation, such as an elevated erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP). A blood test called an ASO titer can detect a recent strep infection. A throat swab might be taken to check for strep throat. A chest X-ray may also be performed to look for signs of sarcoidosis or tuberculosis in your lungs. In some cases, if the diagnosis is unclear or to rule out other conditions, your doctor might recommend a skin biopsy. This involves removing a small tissue sample from one of the lumps for examination under a microscope, which can definitively confirm erythema nodosum.

Treatment options

Treatment for erythema nodosum primarily focuses on managing symptoms and addressing any identified underlying cause. Since the condition often resolves on its own, supportive care and pain relief are key.

If an underlying cause, such as an infection or medication, is identified, treating or removing that trigger is the first step. For symptom relief, your doctor may recommend rest and elevating your legs to help reduce swelling and pain. Applying cold compresses to the affected areas can also provide comfort. Over-the-counter pain relievers, such as nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen or naproxen, can help manage pain and inflammation. In some cases, your doctor might prescribe stronger medications. These can include potassium iodide, which may help clear the lumps, or oral corticosteroids, which are powerful anti-inflammatory drugs reserved for severe cases or when other treatments haven't worked. Compression stockings may also be suggested to help with swelling and discomfort.

Recovery & outlook

Erythema nodosum usually has a good outlook, with most cases resolving completely on their own within a few weeks. The lumps typically fade, though they may leave temporary bruise-like discoloration on the skin.

In most instances, the lumps of erythema nodosum disappear within three to six weeks, though some cases might take up to two months to fully resolve. Once the lumps are gone, they usually do not leave permanent scars. However, the skin where the lumps were located might show a temporary brownish or yellowish discoloration, similar to a fading bruise. While erythema nodosum often resolves without further issues, it can sometimes recur. This is more likely if the underlying cause was not fully identified or treated. If your erythema nodosum is linked to a chronic condition, such as inflammatory bowel disease, managing that condition effectively can help prevent future episodes. Your doctor can provide guidance on managing your specific situation and outlook.

When to see a doctor

You should see a doctor if you develop new, painful, red lumps on your legs or other parts of your body. It is especially important to seek medical attention if these lumps are warm, tender, or accompanied by other symptoms like fever, joint pain, or a general feeling of being unwell.

Prompt medical evaluation is important to ensure that the lumps are indeed erythema nodosum and not another, potentially more serious, skin condition. Your doctor can also help identify any underlying cause that might require specific treatment. Early diagnosis and treatment of an underlying condition can help resolve the erythema nodosum and prevent potential complications. Do not try to self-diagnose or treat the condition, as a proper medical assessment is crucial for an accurate diagnosis and appropriate care plan.

Frequently asked questions

Can erythema nodosum be a sign of something serious?

While erythema nodosum itself is usually not serious and often resolves on its own, it can sometimes be a sign of an underlying medical condition. These can include infections like strep throat or tuberculosis, or inflammatory diseases such as sarcoidosis or inflammatory bowel disease. Your doctor will work to identify any underlying cause.

Is erythema nodosum contagious?

No, erythema nodosum is not contagious. It is an inflammatory reaction within your body and cannot be spread from person to person through contact. However, if an underlying infection is causing it, that infection might be contagious.

What is the difference between erythema nodosum and a bruise?

Erythema nodosum lumps are typically firm, tender, and warm, and they develop due to inflammation in the fat layer under the skin. While they can change color like a bruise as they heal, a bruise is caused by bleeding under the skin from an injury. Erythema nodosum lumps usually appear without a direct injury.

Can stress cause erythema nodosum?

The provided sources do not directly list stress as a cause of erythema nodosum. However, stress can sometimes worsen or trigger symptoms of underlying conditions that are known causes, such as inflammatory bowel disease. The primary triggers are infections, inflammatory diseases, and certain medications.

How long do the lumps of erythema nodosum last?

The lumps of erythema nodosum typically last for about three to six weeks. In some cases, they may persist for up to two months. They usually fade away on their own without leaving scars, though temporary skin discoloration, similar to a bruise, might remain for a while.

Are there any foods I should avoid if I have erythema nodosum?

The provided sources do not mention specific foods to avoid for erythema nodosum. Treatment focuses on managing symptoms and addressing any underlying cause. If your erythema nodosum is linked to an underlying condition like inflammatory bowel disease, your doctor may provide dietary advice related to that specific condition.

Sources

• MedlinePlus — Erythema Nodosum
• Mayo Clinic — Erythema Nodosum
• Cochrane Library — Erythema Nodosum