Transillumination of renal biopsy specimens for rapid identification of glomeruli

Increasing numbers of percutaneous needle biopsies of the kidney rather than open renal biopsies are being performed in community hospitals as more trained nephrologists are available for consultation. There is a growing desire for ancillary studies such as immunofluorescence (IF) and electron microscopy (EM) in addition to light microscopy (LM). The pathologist is faced with the problem of confirming the adequacy of the biopsy and dividing the specimen for the indicated studies. Because in most instances the diagnostic changes are within glomeruli, one must be certain that all three specimens include renal cortex and contain glomeruli in adequate number. To be useful, the procedure must be rapid. Tissue for IF should be frozen as quickly as possible. Confirmation by frozen section cannot be used because of the small size of the specimen and the need to retain tissue for the studies mentioned above.A hand lens, inverted ocular, or dissecting microscope can be used to identify glomeruli if they contain many red blood cells: but, if little glomerular blood is present they are difficult or impossible to visualize by these methods. With transillumination of the biopsy specimen using an ordinary light microscope under lowest power, one can usually visualize bloodless, normal, or pathologically damaged glomeruli easily and rapidly.Although some sort of preliminary visualization of percutaneous needle biopsies of the kidney is probably currently in use in most large renal pathology services, we have seen no report of the use of the transillumination method. We feel that it greatly simplifies handling of these specimens, insures that glomeruli are present for the various studies, and saves technologists' time