Patterns of metastasis can be identified and characterized in patients with tumor- negative SNs.

After a negative SN biopsy procedure 11 patients developed regional lymph node metastases during follow-up.

The incidence of false- negative SN and the rate of recurrence in the regional node basin have been low.

Histopathologic reexamination of SNs from the 69 patients identified 9 patients with false- negative SNs; 2 of these had same-basin recurrences.