We have found that the biology of the primary tumor is conferred to the lymph node in that the presence of ETE leads to a significantly higher incidence of ENE. Awareness of this relationship should be accounted for in the management of primary and recurrent lymph nodes. This study shows that minimal ETE is a significant predictor of ENE. Although long-term survival and recurrence follow-up is not available for the majority of patients in this series, the presence of ENE as a surrogate for more aggressive disease biology and its strong association with minimal ETE supports the upstaging of patients with minimal ETE.

RESULTS indicate that clinically nonevident, small lymph nodes are at risk of harboring aggressive disease biology reflected in ENE. A total of 47% of all nodes fell within Randolph et al.'s classification of "small" lymph nodes, while 59% of the nodes with ENE were <1.5 cm-the threshold size that was deemed to be prognostically significant by Ito et al. It is apparent that clinically nonevident regional lymph nodes can have adverse histologic features and that the previous presumption that nodes with ENE only appear in clinically evident, macroscopic nodes is flawed.