Pathologic examination of renal cell cancer by means of step‐sectioning

Abstract

Background: Because incidental detection of small renal cell cancers (RCC) has recently become increasingly common, nephron-sparing surgery for these cases has been more widely performed.Renal cell cancer was investigated by means of step-sectioning in order to determine which cases were suitable for nephron-sparing surgery and how it should be performed. Methods: Pathology specimens obtained from 90 cases of radical nephrectomy were examined in 5 mm sections. We excluded large and invasive tumors from the present study. Particular attention was given to satellite tumor nodules (STN), pseudocapsules of the main tumor and vascular invasion.Results: Satellite tumor nodules of cancer (STN-Ca) were found in seven of 90 cases (7.8%). Tumor size and grade was not correlated with the existence of STN-Ca. The distance between the main tumor and STN-Ca varied, with the pathology of the STN-Ca mostly resembling that of the main tumor. Pseudocapsules of the main tumor were incomplete in 53 cases (58.9%), but extracapsular invasion of more than 1 mm was not seen in tumors less than 50 mm in diameter. Through step-sectioning, a further six cases with microscopic vascular invasion were found. Vascular invasion within the main tumor was confirmed in 16 of 17 cases (94.1%) and within normal renal tissue in only one case. Conclusions:The incidence of existing STN-Ca was not high (7.8%) in the present study, we had not any characteristics in the cases with STN-Ca. As STN-Ca were rarely near the main tumor, we could not expect to resect STN-Ca with main tumor, resection to more than 1 mm outside the pseudocapsule was needed for complete resection of main tumor less than 50 mm in diameter. Normal renal tissue between the tumor and pelvis is a requirement for selecting appropriate cases in nephron-sparing surgery, but we could not remove the risk of leaving STN-Ca completely.