Erythema Nodosum (EN) is a type of inflammatory skin condition that causes the formation of painful, red bumps or nodules under the skin, typically on the shins. It is considered an immune-mediated reaction and can be associated with a variety of underlying conditions.
Key Features of Erythema Nodosum:
- Symptoms:
- Painful red or purple nodules: These lumps are typically firm, tender, and located on the front of the lower legs (shins), but they can also appear on the arms or other parts of the body.
- Inflammation: The affected areas may be swollen, warm to the touch, and may become increasingly painful over time.
- Fever: Some individuals may experience mild fever and general malaise.
- Joint pain: Pain and discomfort in the joints, especially in the knees and ankles, can also occur.
- Lumps: The nodules typically appear in clusters and may vary in size. They may last for a few weeks and eventually fade without leaving scars, although they can cause temporary skin discoloration.
- Causes:Erythema nodosum is often triggered by an underlying condition or infection. Some common causes include:
- Infections:
- Streptococcal throat infection (common in children)
- Tuberculosis
- Fungal infections
- Viral infections, including hepatitis, mononucleosis (Epstein-Barr virus), or HIV
- Autoimmune diseases:
- Inflammatory bowel disease (such as Crohn's disease or ulcerative colitis)
- Systemic lupus erythematosus (SLE)
- Rheumatoid arthritis
- Medications: Certain medications, including antibiotics, oral contraceptives, and sulfonamides, can trigger erythema nodosum.
- Pregnancy: Hormonal changes during pregnancy can increase the risk of developing erythema nodosum.
- Other conditions:
- Sarcoidosis (an inflammatory disease that affects multiple organs)
- Behçet’s disease (a rare autoimmune condition)
- Diagnosis:
- Physical examination: A doctor typically diagnoses erythema nodosum by examining the characteristic red, painful bumps on the skin, especially on the shins.
- Medical history: A thorough review of recent infections, medications, and any associated systemic symptoms (such as joint pain or fever) will help identify underlying causes.
- Biopsy: In some cases, a skin biopsy may be done to rule out other skin conditions and confirm the diagnosis.
- Blood tests: Blood tests may be performed to check for infections or autoimmune diseases, including tests for streptococcal infection, tuberculosis, and inflammatory markers like ESR (erythrocyte sedimentation rate) and CRP (C-reactive protein).
- Chest X-ray: A chest X-ray may be used to check for conditions like sarcoidosis or tuberculosis that could cause erythema nodosum.
- Treatment:Treatment for erythema nodosum focuses on managing symptoms and addressing any underlying condition that may be contributing to the inflammation:
- Rest and elevation: Elevating the legs can help reduce swelling and alleviate discomfort.
- Nonsteroidal anti-inflammatory drugs (NSAIDs): Over-the-counter pain relievers like ibuprofen or naproxen are commonly used to reduce pain and inflammation.
- Corticosteroids: In more severe cases or if the condition is persistent, oral or topical corticosteroids may be prescribed to reduce inflammation.
- Treatment of underlying conditions: If an infection, autoimmune disease, or other underlying condition is identified, treatment will focus on managing that specific cause (e.g., antibiotics for a bacterial infection, immunosuppressive drugs for autoimmune diseases).
- Compression stockings: For some patients, wearing compression stockings may help reduce swelling in the legs.
- Prognosis:
- Erythema nodosum usually resolves on its own within a few weeks to a few months, but it may recur, especially if the underlying cause persists or is not treated.
- Skin discoloration: While the nodules often heal without leaving scars, they may cause temporary skin discoloration or dark patches.
- Chronic erythema nodosum: In some cases, erythema nodosum can become chronic, especially if there is an ongoing underlying disease (such as inflammatory bowel disease or sarcoidosis).
- Complications:
- Recurrent outbreaks: In cases where erythema nodosum is triggered by chronic conditions, outbreaks may recur.
- Discomfort and pain: The painful lumps may cause significant discomfort, particularly when walking or standing.
- Scar tissue: Rarely, if the condition is severe or long-lasting, scarring may occur on the skin.
- Risk Factors:
- Age: It can affect individuals of any age, but it is most common in young adults (usually in their 20s or 30s).
- Gender: It is more common in women than in men.
- Underlying conditions: Having a condition such as autoimmune disease, inflammatory bowel disease, or infectious diseases increases the risk of developing erythema nodosum.
- Medications: Certain medications can increase the risk of erythema nodosum, especially antibiotics and birth control pills.
