Immunofluorescence on paraffin sections pretreated with proteinase for 30 or 60 minutes showed granular IgG deposits in the mesangium and along glomerular capillaries in 15 (out of 18) biopsies (83.3%), granular C3 deposits in 2 biopsies (11.1%), and granular IgA deposits in 3 renal cases with LN (16.6 percent). The gene discussed is C3; the disease is lobular neoplasia.