Evaluation of immunohistochemical fine sectioning for sentinel lymph node biopsy in oral squamous cell carcinoma.

OBJECTIVE: To determine the level of sentinel lymph node sectioning necessary to accurately detect nodal micrometastasis. STUDY DESIGN: Cross-sectional. SETTING: Tertiary care university medical center. SUBJECTS AND METHODS: Fine sections of oral squamous cell carcinoma sentinel lymph nodes previously sectioned at 2-mm intervals in a prospective clinical trial were reexamined. The results yielded from prior hematoxylin and eosin and immunohistochemical staining were compared with results following exhaustive serial sectioning at 150-µm intervals using identical staining methods. These experimental findings were compared with pathologic results of immediate completion selective neck dissection, previously recorded prospectively. RESULTS: Reexamination of 35 sentinel nodes at 150-µm intervals has not revealed any missed micrometastatic disease at 2-mm intervals used initially. Both comparisons of 150-µm sectioning analysis to the original 2-mm section samples and to the neck dissection pathology reports demonstrate a 100% negative predictive value. CONCLUSION: These data suggest that sentinel lymph node sectioning at 2-mm intervals for oral carcinoma using hematoxylin and eosin staining and then immunohistochemical analysis maximizes efficiency, accuracy, and expenditure for the detection of micrometastasis.