Vasculitis simulating eczematous dermatitis due to C2 deficiency.

In a patient with total C2 deficiency and repeated respiratory infections a papulovesicular rash showed to be due to leukocytoclastic vasculitis. The patient's brother also had a total deficiency of C2 but no clinical symptoms. HLA-investigation in both him and the proband showed the genotype commonly reported in cases with homozygous C2 deficiency. Their heterozygous mother and sister had slightly decreased C2 levels.