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.