Investigation of micrometastasis by cytokeratin staining in non-small cell lung cancer patients with tumor negative mediastinoscopic lymph node biopsies

To investigate micrometastasis by using epithelial cytokeratin marker in non-small cell lung cancer (NSCLC) patients with tumor negative mediastinoscopic lymph node biopsies. Micrometastasis were investigated by immunohistochemical staining in 20 patients who were diagnosed as NSCLC with ipsilateral mediastinal lymph nodes (RN2) in CT scan and with negative histopathologic mediastinoscopic lymph node biopsy (pN0). Frozen section was studied with hematoxylin-eosin (HE), a routine histopatological method in lymph nodes taken by mediastinoscopy and in absence of metastasis; resection was applied with thoracotomy in the same session. We studied micrometastasis in lymph nodes, which are taken out by mediastinoscopy and dissected during resection, using both HE and immunohistochemical staining with cytokeratin. All patients were male and median age was 60.9 (51-74) years. In 16 cases epidermoid carcinoma, in 2 cases adenocarcinoma and in 2 cases bronchioloalveoler carcinoma were diagnosed as histopathological types. Cervical mediastinoscopy was performed in 20 patients who were diagnosed as RN2 by thorax CT radiologically, and complete resection was done in pN0 patients. Sixty lymph nodes, 40 of them taken by mediastinoscopy and 20 taken during resection, were stained immunohistochemically in 20 NSCLC patients. Only one lymph node from a single patient was positive after staining. After postoperative staging, 18 patients were at a lower stage, one patient was at the same stage, and one patient with micrometastasis was at an advanced stage. Immunohistochemical staining may be useful in detecting micrometastasis in NSCLC. Standard cervical mediastinoscopy is still gold standard in preoperative staging. Efficiency can be increased by combining mediastinoscopy, a gold standard method in staging, with immunohistochemical methods. © 2013 OMU.