Fingerprint-like straight crystalloid microfilaments in lobular glomerulonephritis

This 64-year-old male presented edema and proteinuria. With increasing renal insufficiency and persistent fever, he died 7 months after the onset of illness, complicated with terminal miliary tuberculosis. All the glomeruli showed sclerotic nodular lobulation and mesangial circumferential interposition with positive immunoglobulin and complement predominantly along the capillary, consistent with lobular glomerulonephritis (LGN) or terminal stage of membranoproliferative glomerulonephritis (MPGN). Electron microscopy revealed subepithelial straight crystalloid microfilaments in the amorphous deposits. These structures possibly represent IgG or its fragment as a component of immune complex crystallized in some particular condition.