Abstract
BACKGROUND AND PURPOSE: ENB is a rare malignant neoplasm that affects the anterior skull base. Disease stage is a significant predictor of survival, in particular the presence or absence of lymph node metastases. Multiple studies have identified the cervical lymph nodes as the most frequent site of spread; however, no studies have attempted to characterize the radiographic appearance of metastatic lymph nodes or identify the primary nodal drainage for these tumors. MATERIALS AND METHODS: We retrospectively reviewed the medical records and imaging examinations of patients with a pathologically proved diagnosis of ENB from a single tertiary care institution from 2004 to 2010. A head and neck radiologist with 9 years of experience in evaluating ENB reviewed the imaging of all patients with lymph node metastases to confirm the lymph node findings. RESULTS: Spread of ENB to cervical lymph nodes was discovered in 14/48 patients (29%). Of the 14 patients, 5 (36%) were discovered to have lymph node involvement at initial staging, while 9 (64%) showed development of disease in the cervical nodes on surveillance examinations. Level II lymph nodes were the most frequently involved (13/14 cases). Levels I (57%) and III (50%) nodes and RPNs (43%) were also frequently involved. Metastatic lymph nodes were predominantly solid and demonstrated marked contrast enhancement, often approaching the degree of enhancement of nearby blood vessels. Metastatic nodes were moderately or highly FDG-avid. CONCLUSIONS: ENB exhibits a predictable pattern of metastasis to cervical lymph nodes, typically spreading first to level II nodes, with frequent involvement of level I and III nodes and RPNs. Metastatic lymph nodes have characteristic imaging features that can assist radiologists in the identification of nodal disease.