Introduction: Carcinoma from almost all the organs has a tendency for regional metastasis. Nodal status is a key prognostic indicator in such patients, particularly with N0 stage. Occult metastasis in the form of micrometastasis (MM) and isolated tumor cells (ITCs), often goes undetected by routine hematoxylin and eosin (H&E) examination using 12 sections for analysis. This limitation could be overcome by combining serial sectioning (SS) with immunohistochemistry (IHC) for the detection of MM. Cytokeratin (CK7) is particularly a useful marker to detect these deposits as their presence has resulted in varied interpretations and different applications of the tumornodemetastasis system. The objective of the study was to detect micrometastases in lymph nodes reported negative on H & E staining by combining SS and IHC and to compare it with conventional H&E staining. Methods: The study was conducted on 181 LNs received from 77 patients which were negative on H &E. The lymph nodes (LNs) positive on H & E were not taken up for the study. IHS with CK7 was performed on these lymph nodes for detection of micrometastsis. Results: The application of combination of SS and IHC using CK7 in our study revealed the presence of MM in 14.36% of the LNs diagnosed as negative on routine H&E examination. Conclusion: In the view of crucial role of occult LN metastasis in prognosis and survival of patients, diagnostic tools such as IHC staining, particularly with CK7, combined with SS should be preferred over conventional methods as they result in upstaging, thus sparing the lowrisk patients the morbidity of unnecessary treatment.

Keywords: Micrometastasis; Lymph Nodes; Immunohistochemistry; Cytokeratin7; Serial Sectioning.