CD79A and proliferative glomerulonephritis: With a diagnostic sensitivity of 100% and specificity of 87%, the combination of purpuric lesions with at least one of the following four clinical criteria and histopathological findings (abdominal pain, polyarthralgia, renal involvement, and leukocytoclastic vasculitis/proliferative glomerulonephritis with perivascular IgA deposits) suggests this vasculitis as the most likely diagnostic hypothesis for our patient [3].