Needle core biopsies are mainly performed for the evaluation of non-neoplastic renal disorders (i.e. “medical kidney” biopsies), renal allografts (i.e. “transplant kidney” biopsies), and mass lesions. It is very important that you determine the biopsy indication before you proceed, as they are processed differently.
For all biopsies, regardless of indication, count the number of renal parenchymal needle cores and measure the length and diameter of each core. Measure any fibrous tissue (i.e. non-renal parenchymal) fragments separately.
For medical and transplant biopsies, identify glomeruli with the help of a dissecting microscope. The specimen should be placed in a petri dish with a few drops of saline. Glomeruli are identified as pink-red round structures, and the medulla appears as pink-red parallel stripes. The pink-red color is due to the presence of red blood cells in glomerular capillaries and medullary vessels.
Medical and transplant biopsies should be received without formalin (i.e. with saline or in special holding media). They are processed according to the lab’s protocol for one or more studies: light microscopy, immunofluorescence, electron microscopy. Consult with an attending renal pathologist if you are unsure how to submit the tissue.
Biopsies of mass lesions may be received with or without fixative and are generally only processed for light microscopy. Intraoperative evaluation by touch prep (prior to being placed in formalin) may be requested by the submitting radiologist.
Received in saline, labeled _____ and “_____”, are __ (number) needle core biopsies of tan-white soft tissue measuring __, __, and __ cm in lengths, respectively; each is 0.1 cm in diameter. There are also separate gray-tan, fibrous, soft tissue fragments in the container measuring __ x __ cm. Portions of the core biopsies are submitted for special studies as follows: a ____ cm portion from one core is frozen for immunofluorescence microscopy; a ____ cm portion from one core is held for electron microscopy. The remaining tissue is entirely submitted for light microscopy as follows: