A case of mistaken identity: unilateral erythema elevatum diutinum associated with IgA paraproteinaemia.

We report the case of a 27-year-old woman presenting with unilateral painless nodules of the left hand following trauma. Initially diagnosed as nontuberculous mycobacterium infection and treated with prolonged courses of antibiotics with little improvement, the condition was subsequently diagnosed histologically as erythema elevatum diutinum (EED). The lesion was treated with surgical excision, and the patient remained lesion-free at the 1-year follow-up. Although the lesion was otherwise asymptomatic, further investigation demonstrated an underlying IgA paraproteinaemia. This case should alert physicians to consider the diagnosis of EED in a unilateral presentation, and highlights the importance of investigation for underlying associated haematological disease.