Erythemas — Clinical Case (Wikimedia Commons)

Diagnosis: Erythemas

Watercolour drawing of erythema circumscriptum of an arm. Taken from a child aged three years. Keywords: Godart, Thomas. Clinical photograph sourced from Wikimedia Commons (CC BY 4.0). Attribution: Godart, Thomas.

Clinical Presentation

Erythema multiforme: target lesions with three zones on acral surfaces. Erythema nodosum: tender erythematous nodules on anterior shins. Erythema annulare centrifugum: annular plaques with trailing scale.

Clinical History

EM: preceding HSV infection or mycoplasma. EN: sarcoidosis, IBD, medications, infections, pregnancy. EAC: associated malignancy, infections, medications. Erythema ab igne: chronic heat exposure history.

Treatment

Treat underlying cause. EM: HSV prophylaxis if recurrent. EN: NSAIDs, potassium iodide, treat underlying condition. EAC: address underlying trigger. Supportive care and symptom management.

Differential Diagnosis

Erythema multiforme, Erythema nodosum, Urticaria, Sweet syndrome, Vasculitis, SJS

Key Learnings

True target lesions (three zones) of EM are distinct from urticarial plaques. Erythema nodosum is a panniculitis — biopsy should include subcutaneous fat. Always investigate for underlying etiology.

Tags: erythema, inflammatory, vascular, targetoid