Invasion of the microcirculation in head and neck cancer.

Microvascular invasion by carcinoma cells is one of the first steps for the potential development of metastases. Because of an extensive and destructive triage of the cells, the histologic finding of such invasion is not pathognomonic for the establishment of metastases. From a practical standpoint, microvascular invasion correlates with an increased incidence of lymph node metastases, but not with distant spread.