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Renal Biopsies Biopsies will generally be performed in: Ultrasound and CT, MUSC 3rd floor; or Roper Ultrasound and CT (Roper 1st floor) The following items are essential and should be available on the cart (for MUSC biopsies) or in the carrying caddy (for Roper): wooden sticks, formalin containers, blades, glutaraldehyde containers, Michel’s fixative containers, labels, pen, extra requisition forms, and magnifying lens (used at Roper in lieu of dissecting microscope) When you arrive at the site, plug in the microscope (MUSC), label your container(s), and check the requisition sheet for accuracy and completeness. Add any additional history you can get from the chart, or the patient. A technically adequate renal biopsy contains 10 glomeruli and 2 arteries. To achieve this, the tissue procured must be cortex (not medulla), and must be of an adequate quantity. The microscopic appearance of cortex is tan with glomerular blushes. The glomeruli may or may not be visible as blushes due to the relative content of blood. They may also appear as knobs along the sides of the core biopsy. The medulla will often be paler (whitish), and is usually identified by red stripes (the vasa recta). Adipose tissue will be yellowish to tan, and appears bubbly. Muscle tissue is translucent pink/tan and can be teased into bundles. Native (non-transplant) kidney biopsies will almost always be procured for immunofluorescence (IF) microscopy and electron microscopy (EM) in addition to light microscopy. Generally, transplant kidney biopsies will be procured for light microscopy only (looking for rejection or infection), unless the patient had a native kidney disease that can recur in the transplant, and requires IF or EM for diagnosis or grading. Such conditions include: focal segmental glomerulosclerosis (FSGS), membranoproliferative glomerulonephritis (MPGN), membranous GN, IgA nephropathy, Henoch-Schonlein Purpura (HSP), Anti-GBM nephritis, and hemolytic uremic syndrome (HUS). One good core (all cortex) is often adequate when only light microscopy is to be performed (ie, transplant kidneys). Usually two good cores are needed when dividing the tissue for LM, IF, and/or EM. When to ask the operator for additional tissue: 1) A significant portion of the biopsy is fat, medulla, muscle, blood clot, etc (not cortex). 2) When procuring tissue for IF and EM, and dividing the tissue will limit the amount for light microscopy too severely. 3) The core is all cortex, but is shorter than usual (ie, not enough volume to ensure adequate # of glomeruli). A 15-gauge needle should be used in most biopsies. An 18-gauge needle may be used in children, or within the first couple of weeks after transplantation. A general guideline when dividing the tissue: 70% for LM, 20% for IF, and 10% for EM. This can be altered as needed depending on the relative value of each modality in light of the patient’s disease state. Immunofluorescence: A 2-3 mm portion of cortex core is placed in Michel’s fixative (black top). Depending on the patient’s disease state (and the value of IF vs. LM vs. EM) you may choose to put in 2 pieces. Note: Take care not to use a formalin-contaminated wooden stick when transferring tissue into the vial for IF, because this induces autofluorescence. Electron microscopy: A 2 mm portion of cortex is placed in glutaraldehyde (teal blue top vial). Note: Tissue can be transferred later from Michel’s fixative to other fixatives such as glutaraldehyde, but tissue cannot be transferred into Michel’s from other fixatives. All glass slides, wooden sticks, and blades go in a sharps container. Renal transplant biopsies received before noon (or in the very early afternoon in special cases) are rushed and read out the same day they were procured. Take the specimen and paperwork directly to histology, giving the back copy of the paperwork to Accessioning so they can assign an accession number. All other routine (native) biopsies are dropped at the accessioning window with the paperwork. The portions of the specimen for EM and IF can be taken directly to the Special Stains lab (place in top shelf of in-tray on Rena’s desk just inside Special Stains). Please place a red dot sticker on each of the 3 sheets of the accessioning paperwork for all lupus cases (this marks the case for extra slides to be cut for a study).
Conditions in which IF is useful/important:
Conditions in which EM is useful/important:
Note: If a patient is known to have lupus nephritis and not enough tissue is obtained for LM, IF, and EM, then LM is most important, as the WHO classification and activity and chronicity indices are based on light microscopic findings. |
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Copyright © 2005 Madory Consulting
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