Abstract: Abstract Objective: to discuss the clinical pathology features and biologic characters of lung primary signet-ring cell carcinoma. Methods: to observe the histopathology features of 8 cases of lung primary signet-ring cell carcinoma，immunohistochemistry staining with cytokeratin pan (CKpan), cytokeratin 7 (CK7), cytokeratin 20 (CK20), vascular endothelial growth factor(VEGF) and thyroid transcription factor-1 (TTF-1)and special staining with AB and PAS in the all cases. Results: patients with lung primary signet-ring cell carcinoma present with cough and expectoration, and clinical symptoms are deficient with specificity. Nodule masses are present in periphery of lung by imaging, which have no unclear border and the diameters are 2.5-5.5cm. tumor cells are moderate size， round， and contain considerable mucin， which push against cell nucleus creating a signet ring cell appearance under light microscope. These special stains with AB and PAS are all positive. The immunohistochemical stains with CKpan and carcinoembryonic antigen (CEA) are all positive, 7 of 8 patients with CK7, TTF-1 and VEGF are positive, 1 of 8 patients with CK20 is positive.Conclusion: lung primary signet-ring cell carcinoma is scarce， high malignancy， tending to spread and metastasis. The final diagnosis depends on pathology and immunohistochemistry stain, TTF-1, CK7 and CK20 may help differentiate primary and metastatic signet-ring cell carcinoma.

Key words: carcinoma, signet ring cell lung neoplasms neoplasms, multiple primary immunohistochemistry pathology, clinical, 临床