Histologic Characteristics of Renal Cell Carcinomas with Lymph Node Metastasis

Background: This study was conducted to determine if there are any specific histologic features that are associated with lymph node metastasis in renal cell carcinoma (RCC). Methods: TNM classification, histologic grade, mean nuclear volume, cell type, and histologic architecture of the tumors were evaluated in 66 patients who had undergone nephrectomy and lym-phadenectomy for RCC. In the 18 patients with positive lymph node metastasis, both primary lesions and metastatic lymph nodes were evaluated. Results: Lymph node status was correlated with primary tumor stage, venous involvement, and distant metastasis. The tumor grade was higher, and the mean nuclear volume was larger, in both primary and metastatic lesions of RCCs with lymph node metastasis than in tumors with no metastasis. In primary lesions of RCCs with lymph node metastasis, clear cell, alveolar, or cystic patterns were observed less frequently, and granular or spindle/pleomorphic cells and papillary or solid patterns, were observed more frequently, as compared to those lesions without metastasis. Comparison between primary and metastatic lesions in individual patients revealed no significant difference in grade or mean nuclear volume. The development of new cell types or histologic architectures, which was not noted in the primary lesions, was also a rare event in the metastatic lesions. Conclusion: Several characteristic histologic features, which may reflect the increased metastatic potential of the tumor, were observed in both primary and metastatic lesions in cases of RCC with lymph node metastasis. No substantial difference in histologic features was observed between the primary or metastatic lesions of individual patients.