A. Suggestions for Processing Specimens

The pathologist's contributions to the care of patients with renal neoplasms are: histological classification grading of malignancy staging Thus, the specimen should not be bivalved or otherwise dissected by the surgeon. If possible, the specimen should be brought immediately and without fixative from the operating room to the laboratory. Try to convince your surgeon! Specimen processing protocol: Photograph the intact specimen first (optional). If there seems to be a penetrating tumor, ink the surface prior to opening the perirenal fat/capsule. This helps to distinguish true tumor penetration of the margins from artefactual spread (very important for pediatric neoplasms !). The initial bivalving incision should pass through the midline of the kidney in the coronal plane, except when the tumor protrudes eccentrically from the kidney and the greatest diameter would not be cut in that plane. Next, remove the perirenal fat (Gerota's fascia) with blunt dissection from the capsule and examine the surface (look for adenomas, adrenal rests, and other subcapsular lesions). In tumors of adults, if parts of the capsule are adherent to the tumor, dissect around them, leaving them in place so that they can be taken for histologic examination. In pediatric tumors the capsule retracts when the first cut is made and this may obscure the relationship of tumor, pseudocapsule, renal capsule and perirenal tissue. Thus, the renal capsule and perirenal tissues (there is much less fat in Gerota's fascia in children than in adults) should not be dissected from the kidney and tumor. Instead, immersion of the specimen in formalin in the refrigerator for an hour or two can be used to make the outer layers of the specimen firmer and then the specimen should be dissected with parallel slices so that the relationship of the tumor to surrounding tissue can be fully evaluated. Use the first cut surface to collect tumor and kidney tissue for special purposes (EM, imprints, flow cytometry, cytogenetics, tissue culture, snap freezing etc.) Photograph the bivalved kidney and weigh and measure the specimen (both halves). Since renal tumors in children often dwarf the small kidneys of these patients, the weight of the specimen often is given as the weight of the tumor. Next make a series of parallel slabs in the sagittal plane at 2-3 cm intervals. Place the entire specimen in a large container of buffered formalin for fixation overnight. Refrigerated fixation is superior to fixation at room temperature. Fixation before further sampling may delay the final report, but the results are much better. Before further gross inspection and description are done cut the fixed slices in 1 cm intervals with a long large sharp knife. For gross description, bear in mind: tumor form: ball shaped, polygonal, uni- or multinodular, uni- or multifocal. tumor border: sharpness of margins, pseudocapsule tumor color: yellow, grey-white, brown, tan-brown, beige structural features of the tumor: homogeneous, solid, cystic, papillary, whorls signs of regression: necrosis, hemorrhage, scars, pseudocysts extension of the tumor: consider the staging criteria (restricted to the kidney, infiltration of the perirenal adipose tissue or the hilar region (renal sinus), macroscopic invasion of hilar veins or pelvis, look for lymph nodes and dissect the adrenal) Histological sampling: Separately label each block, and clearly document the exact site from which each block is obtained. Take one block from each tumor area that differs in color, especially from areas which are white and grey. Sections from the periphery of the tumor are superior to those of the center because they show the interface with the kidney and other tissues and because necrosis is more common near the center. One generous section of tumor per 2 cm of tumor diameter is probably sufficient. Additional sections should include renal pelvis, renal artery and vein, ureter, lymph nodes, adrenal, and normal kidney