Organ-preserving surgery in renal cell carcinoma: tumor enucleation versus partial kidney resection.

Organ-preserving surgery is attempted in cases of small renal cell carcinoma, especially when such tumors occur bilaterally or in an anatomical or functional solitary kidney. It is still a matter of debate how much of the peritumoral renal tissue has to be removed for optimal cure rates. Enucleation of the neoplasm as well as partial nephrectomy have been advocated. The relation of renal cell carcinomas to their pseudocapsule and to the adjacent renal parenchyma was examined using microangiographic and histopathologic techniques. In a number of cases in our series a total or partial enucleation ex situ permitted an investigation of the enucleate and tumor bed. The pseudocapsule of all tumors was invaded by neoplastic cells and the surrounding renal parenchyma was often infiltrated by the carcinoma, even around some of the smallest tumors. Comparison of tumor vascularization with the histologic features led to the suggestion of a more aggressive behavior of renal cell carcinomas once they have exceeded a certain size. Thus, in contrast to larger carcinomas, tumors with a diameter of less than 6 cm most often show a radial vascular pattern and lack central necrosis. These parameters can be evaluated by noninvasive investigative techniques. Smaller tumors appear amenable to conservative surgical treatment; however, in view of our histopathologic findings, a sufficiently wide margin of adjacent renal parenchyma should always be removed with the tumor.