ObjectiveTo elucidate the clinical pattern of pulmonary lymph node metastasis and the significance of station No.12 and No. 13 lymph nodes biopsy in patients with non-small cell lung cancer (NSCLC). MethodsThirty-eight NSCLC patients underwent standard radical resection of pulmonary carcinoma and systemic lymphadenectomy between January 2015 and June 2015. There were 29 males and 9 females with a mean age of 61.1±15.4 years (ranged from 44 to 73 years). There were 20 patients of squamous carcinoma, 17 patients of adenocarcinoma and 1 patient of sarcomatoid carcinoma. All patients didn't receive radioor chemotherapy before the operation. All the lymph nodes in the surgical specimens were marked and sampled for pathology examination. ResultsWe obtained 652 lymph nodes in total (17.2 per patient). Seventy-eight lymph nodes of 24 patients showed lymphatic metastasis with a metastasis degree of 12.0% (78/652) and a metastasis rate of 63.2% (24/38). Among which there were 22 patients of N1 metastasis, 10 of N1+N2 and 2 of N2 skipping metastasis. Routine pathological examination of N1 metastasis demonstrated 12 patients of positive station No.12 and No.13 lymph nodes with the metastasis rate of 31.6%. The total amount of dissected lymph nodes was 95, among which there were 14 lymphatic metastasis with the metastasis rate of 14.7%. Four patients with nodal involvement in lymph node stations No.12 or No.13 were identified from 18 patients without mediastinal and intrapulmonary lymph node metastases confirmed by routine pathological examination. The detection rate was 22.2% (4/18) and the rate of N1 missed diagnosis was 33.3% (4/12). Univariate and multivariate analysis suggested that the metastasis degree of pulmonary lymph nodes of station No.12 and No.13 was associated with tumor differentiation grade (χ2=6.453,P=0.011), while it didn't show any significant differences as to pathology subtype (χ2=0.118, P=0.732), tumor size (χ2=0.930, P=0.759), or tumor classification (χ2=1.648, P=0.199). ConclusionPulmonary lymph node metastasis occupies an important place in the process of lung cancer metastasis. Patients with NSCLC especially those of poorly differentiated should be pathologically examined regularly in order to improve the accuracy of staging.