Metastatic lymph nodes in urogenital cancers: contribution of imaging findings

The presence of nodal metastasis in patients with urogenital malignancies is an important factor for prognosis, and radiologic identification of enlarged nodes greatly affects treatment choices. Radiologic evaluation for nodal metastases is usually performed with computed tomography, but magnetic resonance imaging is also useful in evaluating primary and nodal metastases in pelvic tumors. On these cross-sectional modalities, nodal metastases are usually suspected according to location and size criteria. Although there has been no general consensus on the criteria, a short axis diameter of 8 to 10 mm is generally applied. However, radiologic evaluation does not always provide sufficient accuracy for nodal staging because of an inability to diagnose smaller metastatic lymph nodes. The clinical significance of a radiologic recognition of enlarged nodes also differs by cancer type in relation to differences in staging systems and treatment. The presence of regional lymphadenopathy in patients with renal cell carcinoma often alters surgical methods, whereas the presence of regional lymphadenopathy is an indication of systemic chemotherapy in patients with cancers of the urinary tract, prostate, and testicles. In this report, preferential sites and staging of nodal metastasis and contributions of radiologic imaging are reviewed for each urogenital cancer.