Erythema Nodosum

Key points

• Erythema nodosum: tender erythematous nodules on the shins (panniculitis).
• Causes: streptococcal infection · sarcoidosis (Löfgren's if with bilateral hilar lymphadenopathy + fever) · TB · IBD · drugs (sulfonamides, OCP) · pregnancy.
• Investigate: ASO titre, CXR (hilar lymphadenopathy), consider TB/IBD workup.
• Usually self-limiting over weeks; treat the cause; NSAIDs for symptoms.
• Löfgren's syndrome = erythema nodosum + BHL + fever — good prognosis in sarcoidosis.

Decision points in this pathway

• Erythema nodosum + bilateral hilar lymphadenopathy + fever?

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