Patterns of enlarged lymph nodes in patients with metastatic renal cell carcinoma.

Objective: We reviewed the imaging studies of patients with known metastatic renal cell carcinoma (RCC) in order to more accurately assess where retroperitoneal lymphadenopathy occurs.

Methods: The database of patients with metastatic RCC was reviewed and 101 patients were found from 2002 to 2006. Each patient's CT scans were then reviewed. Twenty-seven retroperitoneal sections were defined for each patient, with 3 positions in each of the x-, y-, and z-axis. Lymph nodes greater than 1 cm were then counted for each section.

Results: Of the 101 patients, 31, of whom 28 qualified, were found to have retroperitoneal lymphadenopathy of a least 1 cm or greater. Two-thirds of nodes (87 out of 124) exhibited a suprahilar, intra-aortocaval, and retro-aortocaval trend of lymph node enlargement. Three patients (11%) had isolated infrahilar nodes, while 8 patients (29%) exhibited a skip lesion pattern by imaging criteria. Only 4 patients (14%) were noted to have lymph nodes that were confined to the ipsilateral (paraaortic or paracaval) nodes in the perihilar and infrahilar region, which would be readily accessible during renal surgery.

Conclusions: Lymphatic drainage in RCC is ill-defined, likely due to multiple lymphatic outflow channels. However, after a review of retroperitoneal lymphadenopathy imaging in patients with known metastatic RCC, there does seem to be a cephalad, posterior, and medial drainage pattern.