Renal Pathology Laboratory
To ensure that renal biopsy material is handled optimally, please follow the proper specimen processing procedures described below and complete the Renal Biopsy Request Form.
These procedures establish criteria for judging specimen adequacy and detail proper specimen division for light microscopy (LM), electron microscopy (EM) and immunofluorescent (IF) studies. They also describe optimal tissue fixation and preparation techniques.
The Renal Biopsy Request Form includes a second page with a collection guide.
Certain essential data must be included on the request form: i.e. patient age and sex; duration of symptoms; concomitant disease processes; physician differential diagnosis; presence or absence and quantity of hematuria and/or proteinuria; and the requesting physician's signature.
This information is absolutely necessary for proper specimen processing and accurate diagnosis.
Click here for complete instructions.
Although open renal biopsies are almost always adequate, percutaneous biopsies provide less tissue and require greater care to ensure appropriate processing. As a consequence, the pathologist should evaluate needle biopsy specimens. The pathologist can identify blood-filled glomeruli with a hand lens, inverted ocular, or dissecting microscope.
Unfortunately pathologically damaged glomeruli are usually bloodless and cannot be easily identified by these methods. However, specimen transillumination with an ordinary light microscope at low power allows visualization of bloodless glomeruli (Hefter & Brennan, 1981). With this technique, glomeruli are pale tan against a darker background. Glomeruli are easier to see in thinner areas and may be difficult to identify with certainty in thick biopsy specimens. Slight flattening of the specimen cylinder by gentle compression with a slide usually remedies this problem and does not produce artifactual changes.
Dividing the Biopsy Specimen
When only a small amount of renal tissue is available, the clinical history and diagnostic considerations will help in deciding which techniques are most likely to provide diagnostic information. However, conventional light microscopy preparation can usually be omitted in such situations, since considerable information can be derived from light microscopy examination of plastic embedded tissue prepared for EM (Hoffman & Flores, 1981).
- First place the 1-2 mm tips of each specimen in 2.5% glutaraldehyde for a needle biopsy specimen.
- For a wedge biopsy, remove a small piece of kidney from the cortex (see diagram) and place it in 2.5% glutaraldehyde.
- Divide the large open renal wedge biopsies equally for LM and IMF studies.
- Dissect the remaining core of the needle biopsy longitudinally with one half submitted in 10% neutral buffered formalin for LM and one half placed in Zeus transport medium for immunofluorescence. This medium may be obtained from the Molecular Diagnostics Lab, WFBMC, 336-716-2756.
Contact Dr. Iskandar at 336-716-2629 if there are questions concerning processing for the renal biopsy. The Renal Biopsy Request Form includes a second page with a Renal Biopsy Collection Guide that you may find helpful.
Sending the Specimen:
Specimens may be sent by courier or by Federal Express/UPS and should be packaged according to the carrier's regulations. Be sure to include the completed Renal Biopsy Request Form.
Please address specimens to:
Dr. Samy Iskandar
Molecular Diagnostics Laboratory
Wake Forest Baptist Medical Center
Medical Center Boulevard
Winston-Salem, NC 27157
Hefter LG, Brennan GG. Transillumination of renal biopsy specimen for rapid identification of glomeruli. Kidney Int. 1981; 20:911-15.
Hoffman EO, Flores TR. High resolution light microscopy in renal pathology. Am J. Clin Pathol. 1981 Nov; 76(5): 636-643.