OBJECTlVE To assess the significance of sentinel lymph node biopsy (SLNB),serial section and cytokeratin immunohistochemical staining in the diagnosis and staging of Stage-cNO oral squamous cell carcinoma (OSCC).METHODS A blue stain,99mTc.dextran SPECT lymphoscintigrapgy and intraoperative γ-ray probes were used to examine the sentinel nodes in 31 cases with Stage-cNO oral cancer.The H&E staining and a cytokeratin AE1/AE3 immunohistochemistry (IHC) assessment,with serial sections,were conducted to provide results obtained from a routine pathological examination of lymph nodes.The value of the routine pathological examination of the sentinel lymph node (SLN),serial sections and IHC determination for cervical Iymph node metastasis of Stage-cNO OSCC was appraised.RESULTS A total of 45,55 and 51 SLNs were examined in 25 (80%),31 (100%) and 30(96.5%) of the cases,by using the blue stain,γ-ray probes,and SPECT lymphoscintigraphy,respectively.The average SLNs found in each case of the groups was 1.4(1 to 3)and there were 1,302 non-NSLNs.Six positive SLN metastases were detected by routine pathological examination,among which 1 case was found to be an accompanied positive metastasis of non-SLN.One positive SLN metastasis was found after examination of serial sections plus routine H&E staining and 2 were detected using serial sections plus AE3 immunohistochemical staining methods.No positive NSLNs were found in the study.CONCLUSION In order to make more progress in accurate SLNB diagnosis,serial sections and OHC (AE1/AE3) methods can be used for examination of the micrometastases which are difficult to identify by routine pathological sections and H&E staining.node,micrometastasis,serial sections,immunohistochemistry.