[CA19-9 Producing Mixed Invasive Mucinous and Non-mucinous Adenocarcinoma;Report of a Case].

A 66-year-old woman was referred to our hospital due to the abnormal shadow on chest X-ray. Computed tomography(CT) scan revealed a mass in the lower lobe of the right lung and the serum CA19-9 level was 1,600 U/ml. Under the diagnosis of adenocarcinoma by bronchoscopic brushing cytology, right lower lobectomy with mediastinal lymph node dissection was performed. Histopathological examination showed mixed invasive mucinous and non-mucinous adenocarcinoma [World Health Organization (WHO) 8th] of stage IA3 with T1cN0M0[ Union for International Cancer Control( UICC) 8th]. Immunohistochemically, the tumor cells were stained positively for CA19-9. Postoperative course was uneventful and the CA19-9 level decreased to 35.5 U/ml 2 months after operation.