66 years old male with positive metastasis mediasyinal lymph node.Fiberbronchoscopic biopsy was revealed squamous cell carcinoma in left lobe and SCLC in right lobe.Immunohistochemical staining of SCLC is revealed a marked positivity for AE1/AE3,Syn,cluster of differentation 56,thyroid transcription factor-1,p63 (few),Ki-67 (80%) and EMA.By contrast,the SCLC was negative for CgA (-), NapsinA and p40. i)Based on the above analysis,the disease diagnosis may be? ii)Associate etiology with clinical manifestation