Renal Lymph Nodes for Tumor Staging: Appraisal of 871 Nephrectomies With Examination of Hilar Fat

Abstract

Context.-Despite decades of research, the role of lymphadenectomy in the management of renal cell carcinoma (RCC) is still not clearly defined. Before the implementation of targeted therapies, lymph node metastases were considered to be a portent of markedly decreased survival, regardless of the tumor stage. However, the role of lymphadenectomy and the relative benefit of retroperitoneal lymph node dissection in the context of modern adjunctive therapies have not been conclusively addressed in the clinical literature. The current pathologic literature does not offer clear recommendations with regard to the minimum number of lymph nodes that should be examined in order to accurately stage the pN in renal cell carcinoma. Although gross examination of the hilar fat to assess the nodal status is performed routinely, it has not yet been determined whether this approach is adequate.Objective.-To evaluate the status of lymph nodes and their rate of identification in the pathologic examination of nephrectomy specimens in adult renal malignancies.Design.-We reviewed the operative and pathology reports of 871 patients with renal malignancies treated by nephrectomy. All tumors were classified according to the seventh edition of the Tumor-Nodes-Metastasis classification. Patients were divided into 3 groups: Nx, no lymph nodes recovered; N0, negative; and N1, with positive lymph nodes. Grossly visible lymph nodes were submitted separately; as per grossing protocol, hilar fatty tissue was submitted for microscopic examination. We evaluated the factors that affected the number of lymph nodes identified and the variables that allowed the prediction of nodal involvement.Results.-Lymph nodes were recovered in 333 of 871 patients (38%): hilar in 125 patients, nonhilar in 137 patients, and hilar and nonhilar in 71 patients. Patients with positive lymph nodes (n ¼ 87) were younger, had larger primary tumors, and had lymph nodes of average size, as well as a higher pT stage, nuclear grade, and rate of metastases. Metastases were seen only in grossly identified lymph nodes (65% hilar, 16% nonhilar); all microscopic nodes were negative. Even with the microscopic examination of fat, hilar lymph nodes were recovered in only 22.5% of patients. A nonhilar route of node metastasis was suspected in 40 patients.Conclusions.-Only grossly identifiable lymph nodes, both hilar and nonhilar, were positive for metastases. Although microscopic examination of the hilar fat increased the number of lymph nodes recovered, the identification rate of these nodes was low (22.5%), and such microscopic nodes were invariably negative. Hence, microscopic examination of the hilar fat may be unnecessary. (Arch Pathol Lab Med. 2013;137:1584-1590 doi: 10.5858/arpa.2012-0485-OA) L ymph node (LN) dissection represents one of the most accurate and reliable staging and therapeutic procedures for the detection of LN involvement in prostate and urinary bladder cancer patients, but its role in the management of renal cell carcinoma (RCC) is less clear.1,2 Before the ...

Renal cell carcinoma staging: pitfalls, challenges, and updates

“…found metastases only in grossly identifiable lymph nodes, suggesting that random microscopic assessment of hilar fat for microscopic lymph nodes may be unnecessary. It is of note that a considerable number of non‐hilar lymph nodes were also found, with a lower rate of positivity (65% hilar; 16% non‐hilar), suggesting that some attention should be paid to possible lymph nodes in other areas of nephrectomy specimens. Previous staging systems have included additional categories for renal cancer depending on the size and number of involved lymph nodes; however, the current AJCC system, like the previous version, continues to include only pN1 for involvement of one or more regional lymph nodes .…”

The ISUP system of staging, grading and classification of renal cell neoplasia

“…Mehta et al (27) examined the entire hilar tissue for histology and found that 80% of grossly visible lymph nodes were positive for tumor, whereas microscopic lymph nodes were all benign.…”

Maximizing Lymph Node Retrieval during Surgical Resection of Wilms Tumor

“…This may in part be because of limited pathologic examination of adjacent renal hilar fatty tissue, as it has been reported to have a low yield for nodes, which are typically negative in adult malignancies. 11 Our results suggest that en bloc only resection of LNs should be avoided as the sole method of sampling with WT. We recommend that surgeons attempt to remove nodes with the tumor specimen, and also submit additional paraaortic, paracaval, and hilar nodes to pathology, as this method yields the most LNs for pathologic evaluation.…”