Paraffin Immunofluorescence: A Role Beyond Kidney Biopsies.

Paraffin immunofluorescence is a well established "salvage" technique in renal pathology when representative glomeruli are not found in the fresh frozen tissue sent for routine direct immunofluorescence studies. A step of enzymatic digestion of the formalin-fixed paraffin-embedded biopsy exposes the antigenic immune complexes and allows staining with fluorochrome-tagged antibodies. We explored the utility of the technique of paraffin immunofluorescence outside the kidney in certain specific scenarios including extra renal amyloid and duodenal macroglobulinemia.