From Maria Picken and colleagues: Renal Lymph Nodes for Tumor Staging: Appraisal of 871 Nephrectomies With Examination of Hilar Fat

http://www.archivesofpathology.org/doi/pdf/10.5858/arpa.2012-0485-OA

Vikas Mehta, Kumaran Mudaliar, Ritu Ghai, Marcus L. Quek, John Milner, Robert C. Flanigan, and Maria M. Picken (2013) Renal Lymph Nodes for Tumor Staging: Appraisal of 871 Nephrectomies With Examination of Hilar Fat. Archives of Pathology & Laboratory Medicine In-Press.

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

Vikas Mehta , MD; Kumaran Mudaliar , MD; Ritu Ghai , MD; Marcus L. Quek , MD; John Milner , MD; Robert C. Flanigan , MD; Maria M. Picken , MD, PhD

From the Departments of Pathology (Drs Mehta, Mudaliar, and Picken) and Urology (Drs Quek, Milner, and Flanigan), Loyola University Medical Center, Maywood, Illinois; and the Department of Pathology, Rush University Medical Center, Chicago, Illinois (Dr Ghai).

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 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 = 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.