Erythema nodosum is an inflammatory skin condition, characterized by the appearance of red, painful, and firm nodules, primarily located on the shins, but which may also extend to the thighs or arms. Also known as panniculitis, this condition, although disconcerting, requires a thorough understanding of its symptoms and causes to be managed effectively.

It often manifests with general symptoms such as a slight fever, joint and muscle pain, and unusual fatigue. These signs frequently precede the appearance of hot and very painful nodules under the skin.

Possible causes include infections (bacterial, viral, or parasitic), autoimmune diseases such as sarcoidosis or Crohn's disease, as well as reactions to certain medications. An accurate diagnosis is essential to provide appropriate treatment.

Finally, beyond treatments, personalized care helps limit potential complications while improving the patient's daily comfort.

Understanding erythema nodosum

Definition and characteristics

Erythema nodosum is an inflammatory dermatological condition that manifests as the appearance of deep and painful subcutaneous nodules. It mainly affects the deep layers of the skin, particularly the dermis and hypodermis.

These nodules, often called bruises, are inflammatory formations of adipose tissue that can reach several centimeters in diameter. Red or purple in color, they are characterized by intense heat to the touch and significant pain.

The revealing symptoms

The signs of erythema nodosum are varied, with general symptoms often preceding skin complaints. Before the appearance of nodules, patients may experience a slight fever, joint or muscle pain, as well as unusual fatigue that sometimes impairs their quality of life.

Subsequently, erythematous plaques or nodules appear, primarily affecting the anterior aspect of the shins. However, they can also affect the thighs or arms, although less frequently. These nodules are palpable, very painful to the touch, and sometimes evolve to resemble bruises. Edema around the ankles and inflammation of the knees may sometimes complete this clinical picture.

Risk factors and underlying causes

Erythema nodosum can be caused by a variety of factors. Common causes include bacterial infections (such as streptococcal pharyngitis or Salmonella enteritis), viral infections (such as hepatitis B and C or HIV), and parasitic infections such as toxoplasmosis.

Drug treatments are also potential triggers. For example, certain antibiotics, estrogens, or proton pump inhibitors such as omeprazole are among the drugs suspected of playing a role in this condition.

Finally, certain autoimmune diseases, such as sarcoidosis, lupus, or chronic inflammatory bowel diseases (such as ulcerative colitis or Crohn's disease), also represent significant risk factors. However, it is important to emphasize that in nearly 50% of cases, no underlying cause is identified, which can complicate management.

Diagnosis procedure for erythema nodosum

Interview and clinical examination

The diagnosis of erythema nodosum begins with a thorough interview of the patient. This interview is essential for gathering information on current symptoms, such as the presence of nodules, fever, joint or muscle pain, fatigue, and other associated clinical signs. It also clarifies the context of onset of symptoms, current or recently taken medications, possible pathologies, as well as the patient's medical, family, and infectious history.

The clinical examination, equally important, must be carried out meticulously. Among the specific points to note, palpation of the nodules proves to be more decisive than their inspection. These nodules, often indicators of the disease, must be well defined, firm, sensitive to the touch, and generally measure between 1 and 5 cm in diameter.

They are generally located on the anterior aspect of the tibias, may be bilateral but asymmetrical, and appear surrounded by diffuse erythema. The clinical examination should also pay attention to potentially associated systemic signs, such as joint swelling or reactive or satellite lymphadenopathy, which may suggest an autoimmune or infectious origin.

Additional tests and examinations

In order to confirm the diagnosis and identify possible underlying causes, various additional tests and examinations are often necessary. For example, a radiograph or a chest scan can detect adenopathies characteristic of pathologies such as sarcoidosis. As for anti-streptolysin O (ASLO) antibody titers or pharyngeal cultures, they are useful for confirming a streptococcal infection.

Skin tests dedicated to tuberculosis or digestive explorations, such as a colonoscopy, may be recommended when there is still a suspicion of chronic inflammatory bowel diseases (IBD).

On the other hand, blood tests are essential to evaluate inflammatory markers (ESR, CRP), the complete blood count (CBC), as well as additional parameters such as transaminases, streptococcal serodiagnosis, and antinuclear antibodies (ANA). In specific cases, an incisional wedge biopsy is considered to formally confirm the diagnosis or demonstrate septal panniculitis associated with a non-specific granulomatous reaction.

Differential diagnosis: distinguishing erythema nodosum from other skin conditions

Performing a differential diagnosis is essential to rule out other skin conditions with similar symptoms. These include infectious cellulitis, thrombophlebitis, lupus, as well as other forms of panniculitis.

By carefully distinguishing erythema nodosum from these pathologies, patients can be offered treatment tailored to their specific condition, thus avoiding inappropriate care that could worsen their situation.

Therapeutic strategies for erythema nodosum

Drug treatments

Drug treatment for erythema nodosum is primarily based on managing symptoms and addressing the underlying cause. For example, nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen or naproxen are commonly prescribed to reduce inflammation and alleviate the pain associated with the nodules.

Potassium iodide may also be an option to reduce inflammation. Although less frequently used, it is prescribed at a dose of 300 to 500 mg orally, usually three times daily. This agent may be beneficial in certain specific cases, although its use is reserved for well-defined situations.

In particularly severe or refractory forms of erythema nodosum, oral corticosteroids may be considered. However, this option is used with caution due to possible side effects, including the risk of worsening an undetected underlying infection.

Non-pharmacological approaches

Non-pharmacological treatments complement pharmacological options and play an important role in patient management. For example, bed rest and leg elevation are often recommended to reduce both pain and inflammation.

Applying cold compresses to the nodules can also provide significant relief. In addition, support devices such as compression stockings and elevation of the lower limbs help to reduce edema while improving the patient's overall comfort. These measures, although simple, are often effective in limiting the intensity of symptoms in most cases.

Follow-up and management of any recurrences

Careful follow-up is essential to monitor the evolution of erythema nodosum and prevent any recurrence. Patients are advised to remain alert to any changes in their skin, and to report the appearance of new symptoms.

In most situations, erythema nodosum resolves spontaneously within 3 to 6 weeks. However, relapses may occur, especially if the underlying cause remains untreated. Constant communication between the patient and the physician is essential in order to best adjust treatments and identify factors that contribute to possible relapses.

Finally, for healthcare professionals, continuing education and practical workshops, such as specialized dermatology CME courses, offer valuable tools to refine their skills in diagnosing and managing these complex pathologies.

Preventing erythema nodosum and its complications

Identification and management of underlying causes

Prevention of erythema nodosum begins with rigorous identification and appropriate management of the underlying causes. It is imperative to effectively diagnose and treat infections, whether bacterial, viral, or fungal, that may be the cause of this condition.

For example, streptococcal infections—often involved in triggering erythema nodosum—require management with specific antibiotics to avoid recurrence. Equally important, autoimmune diseases and chronic inflammatory bowel diseases (such as sarcoidosis, Crohn's disease, or ulcerative colitis) must be monitored and treated in a targeted manner. Appropriate management of these underlying conditions contributes to significantly reducing the risk of developing erythema nodosum.

Tips for reducing the risk of recurrence

To minimize the risk of recurrence, several recommendations are necessary. In case of drug sensitivity, it is strongly advised to identify and avoid triggering substances, such as certain antibiotics, estrogens, or omeprazole. If their use proves indispensable, it must imperatively be done under strict medical supervision.

In addition, a balanced lifestyle plays a key role: a healthy diet, combined with regular physical activity and active stress management, can strengthen the immune system while reducing the risk of recurrence. To further strengthen this prevention, it is recommended to protect against common infections. For example, vaccination against influenza or streptococcal infections can be particularly beneficial in limiting triggering factors.

The importance of regular monitoring

Assiduous medical follow-up is essential not only to prevent potential complications of erythema nodosum, but also to detect any recurrence at an early stage. Patients should be encouraged to carefully monitor their symptoms and report any suspicious changes, whether cutaneous or systemic.

Complementary examinations, such as blood tests or X-rays, can be carried out periodically to monitor disease progression and adjust treatment if necessary. This follow-up also offers the opportunity to act upstream on underlying diseases, thus reducing the risk of severe complications in the long term. Open and regular communication between doctor and patient is an essential pillar in ensuring optimal management of this condition.

Conclusion

Erythema nodosum is an inflammatory skin condition, mainly manifesting as the appearance of painful nodules, often located on the shins. To fully understand this condition, it is essential to comprehend its origins, symptoms, and appropriate therapeutic solutions. Underlying causes, such as infections, drug reactions, or autoimmune diseases, must be identified and managed rigorously.

The diagnosis is based on a careful clinical examination, often supplemented by specific tests to precisely determine the etiological cause. As for treatments, they aim to reduce pain and inflammation through the use of non-steroidal anti-inflammatory drugs, rest, and, if necessary, the administration of corticosteroids.

Regular follow-up is essential, not only to prevent recurrences, but also to manage any associated underlying pathologies. Understanding these different aspects will enable you to act swiftly in the event of symptoms, by consulting a healthcare professional for effective treatment and optimal management of this condition.

FAQ

What are the most common causes of erythema nodosum?

The most frequent causes of erythema nodosum are found in various pathologies or triggering factors. These include streptococcal infections, such as tonsillitis or upper respiratory infections, as well as sarcoidosis. Bacteria such as Yersinia or viruses such as the Epstein-Barr virus are also among the responsible agents. In addition, certain chronic inflammatory bowel diseases, including Crohn's disease or ulcerative colitis, as well as the use of specific medications, may be implicated.

How do the symptoms of erythema nodosum manifest?

Symptoms typically begin with a slight fever (around 38°C to 39°C), accompanied by joint and muscle pain, as well as marked fatigue. After 3 to 4 days, painful and inflamed nodules appear, mainly on the anterior aspect of the tibias and legs, but sometimes also on the thighs or arms.

These nodules are characterized by their red appearance and warmth to the touch. They may be accompanied by edema at the ankles. Over time, these nodules evolve by changing color, going from bright red to blue-violet, then to yellow-green before their complete disappearance.

What are the main treatments to relieve the symptoms of erythema nodosum?

The management of erythema nodosum is based on several approaches:

• Treatment of the underlying cause: When a specific origin is identified, such as streptococcal infection or sarcoidosis, appropriate treatment—such as antibiotic therapy or corticosteroid therapy—should be initiated.
• Rest and supportive care: Bed rest, leg elevation, cold compresses, and the use of compression stockings can help reduce pain and inflammation.
• Anti-inflammatories: Non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen, naproxen or indomethacin may be prescribed. In some cases,potassium iodide may also be beneficial in limiting inflammation.
• Analgesics: Paracetamol or acetylsalicylic acid can be used to manage nodule-related pain.

How is erythema nodosum diagnosed, and what tests may be necessary?

The diagnosis is based primarily on a rigorous clinical examination, with palpation of the nodules and a detailed interview to identify symptoms and their potential triggers. Several additional tests can be performed, depending on the patient's history and the physician's suspicions.

These tests include a complete blood count, a measurement of C-reactive protein, stool tests, throat swabs, and even a chest X-ray. In some complex cases, a digestive endoscopy may be considered. Finally, a skin biopsy may be useful to confirm the presence of septal panniculitis and rule out other potential causes.

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