Differential Diagnosis for Erythema Nodosum
Erythema nodosum is an inflammatory condition characterized by the sudden onset of tender, erythematous nodules or plaques, most commonly on the lower extremities. The differential diagnosis can be broad, reflecting its association with various infectious, inflammatory, and neoplastic conditions. Here is a categorized differential diagnosis:
Single Most Likely Diagnosis
- Sarcoidosis: This is often considered a leading cause of erythema nodosum, particularly when it presents as Lofgren's syndrome, which includes bilateral hilar lymphadenopathy, erythema nodosum, and joint symptoms. Sarcoidosis is a systemic granulomatous disease that can affect multiple organs, including the lungs, skin, and eyes.
Other Likely Diagnoses
- Infections: Such as streptococcal infections, tuberculosis, and fungal infections. These can trigger erythema nodosum through immune-mediated mechanisms.
- Inflammatory Bowel Disease (IBD): Both Crohn's disease and ulcerative colitis are associated with erythema nodosum, reflecting the systemic nature of these diseases.
- Pregnancy: Erythema nodosum can occur in pregnancy, possibly due to hormonal changes or immune system alterations.
- Medications: Certain drugs, including oral contraceptives, sulfonamides, and penicillin, can induce erythema nodosum as an idiosyncratic reaction.
Do Not Miss Diagnoses
- Lymphoma: Although less common, lymphoma can present with erythema nodosum, and missing this diagnosis could have significant implications for patient outcomes.
- Infectious Endocarditis: This condition, although rare, can cause erythema nodosum and requires prompt diagnosis and treatment to prevent serious complications.
- Tuberculosis: Given its potential severity and the importance of early treatment, tuberculosis should not be missed, especially in endemic areas or in individuals with risk factors.
Rare Diagnoses
- Beheet's Disease: A form of vasculitis that can present with erythema nodosum among other symptoms like oral and genital ulcers.
- Sweet Syndrome: Also known as acute febrile neutrophilic dermatosis, it can mimic erythema nodosum but is distinguished by its characteristic histopathology and association with hematologic disorders.
- Erythema Induratum: A form of lobular panniculitis that can present similarly to erythema nodosum but is more commonly associated with tuberculosis and has distinct histological features.
Each of these diagnoses has a different set of implications for patient management and outcome, highlighting the importance of a thorough diagnostic evaluation in cases of erythema nodosum.