In the surgical treatment of lung cancer, systemic mediastinal lymph node dissection, as one important routine procedure, has been accepted by most peers in the world. However, due to the special location of some mediastinal lymph nodes, the difficulty of dissection, and the negative preoperative CT results, the specific scope of lymph node dissection is still controversial. Especially the second group, which is located at the top of thorax, is likely to be overlooked for the above reasons. Here, we report a case of lung adenocarcinoma in which the preoperative CT showed no abnormal lymph nodes in the second group and also no enlarged lymph nodes of the second group were found during the surgery, yet lymphadenectomy was still performed according the routine with the lymph node of station 2 being sampled. In the postoperative pathological report, cancer cells were found in the second group, instead of lung adenocarcinoma, these cells come from thyroid and were proved to be papillary thyroid carcinoma, which is unusual because no obvious indication of thyroid carcinoma was found in preoperative color doppler ultrasound of superficial lymph nodes.

The signal transduction pathways of estrogen receptors (ER) mainly includes gene pathway and non-gene pathway. Studies have shown that the gene pathway of ER is related with the expression of nuclear proteins, and this is the key issue for our current research. With the GEO database analysis, Human centromere protein F (CENPF) is highly expressed in adenocarcinoma of lung (LUAD), and the co-expression of CENPF and ERβ was found in the nucleus of LUAD cells. Meanwhile, CENPF and ERβ2/5 were related with T stage and poor prognosis (P<0.05). Knockdown of CENPF gene significantly inhibited the biological effects of LUAD cells, the tumor growth of mice and the expression of ERβ2/5 (P<0.05). Further, group experiments showed that knockdown CENPF inhibits biological effects of LUAD cells mediated by ERβ pathway. All the results indicated that both CENPF and ERβ2/5 play important roles in the progression of LUAD, and knockdown of CENPF can inhibit the progression of LUAD by inhibiting the expression of ER2/5. Thus, the development of inhibitors against ERβ2/5 subtype and CENPF remained more effective in improving the therapeutic effect of LUAD.