From the Guidelines
Erythema nodosum is a painful inflammatory condition that should be diagnosed on clinical grounds, with treatment based on the underlying cause, and systemic corticosteroids required in severe cases, as stated in the most recent evidence-based consensus 1. The condition is characterized by tender, red nodules typically appearing on the shins, though they can also develop on other areas of the body. These nodules are usually 1-5 cm in diameter, raised, and warm to the touch. Some key points to consider in the diagnosis and management of erythema nodosum include:
- The lesions initially appear as bright red or pink, then gradually change to a bruise-like appearance as they resolve over several weeks.
- Erythema nodosum is not a disease itself but a reaction pattern that can be triggered by various conditions including infections, medications, inflammatory bowel disease, sarcoidosis, or pregnancy.
- Diagnosis is typically made clinically based on the characteristic appearance of the lesions, though a biopsy may be performed in uncertain cases, as noted in 1 and 1.
- Treatment focuses on addressing the underlying cause while providing symptomatic relief, and in severe cases, systemic corticosteroids or other immunosuppressive medications might be necessary, as recommended in 1. The most recent and highest quality study, 1, provides the best guidance on the diagnosis and management of erythema nodosum, and its recommendations should be followed in clinical practice.
From the Research
Erythema Nodosum Characteristics
- Erythema nodosum is a cutaneous reaction consisting of inflammatory, tender, nodular lesions, usually located on the anterior aspects of the lower extremities 2
- The typical eruption consists of a sudden onset of symmetrical, tender, erythematous, warm nodules and raised plaques usually located on the shins, ankles and knees 2
- The nodules show a bright red color at first, but within a few days they become livid red or purplish, and finally they exhibit a yellow or greenish appearance taking on the look of a deep bruise 2
- Ulceration is never seen and the nodules heal without atrophy or scarring 2
Erythema Nodosum Causes and Associations
- Erythema nodosum can be associated with a wide variety of diseases, including infections, sarcoidosis, rheumatologic diseases, inflammatory bowel diseases, medications, autoimmune disorders, pregnancy, and malignancies 2, 3, 4
- The most common identifiable causes are streptococcal infections, primary tuberculosis, sarcoidosis, Behçet disease, inflammatory bowel disease, drugs, and pregnancy 3, 5
- Erythema nodosum is presumed to be a hypersensitivity reaction and may occur in association with several systemic diseases or drug therapies, or it may be idiopathic 5
Erythema Nodosum Diagnosis and Treatment
- Laboratory and instrumental examinations should be performed to identify any underlying trigger disease 5
- Treatment of erythema nodosum should be directed to the underlying associated condition, if identified 2, 4
- Symptomatic treatment options include nonsteroidal anti-inflammatory drugs, potassium iodide, and colchicine 6
- Systemic corticosteroids are rarely indicated in erythema nodosum and should only be used after ruling out an underlying infection 2