histologic confirmation of this lesion is difficult , although it is very important for decision of treatment method.1 various methods , including endoscopic ultrasound - guided fine needle aspiration ( eus - fna),2,3 eus - guided trucut biopsy ( eus - tcb ) , endoscopic submucosal - mucosal resection ( esmr),4 and open surgery have been reported to be used for confirmation of the diagnosis.5 however , the best method for tissue acquisition has not been established yet . here , we report a case with a 12 cm submucosal signet ring cell type adenocarcinoma , diagnosed by eus - tcb and immunochemical studies . a 57-year - old man presented with epigastric pain and a 6 kg weight loss over 3 months . laboratory tests at admission showed white blood cell count of 13,050/mm ( normal range , 4,800 to 10,800 ) , hemoglobin 14.2 g / dl ( 13 to 18 ) , carcinoebryonic antigen 1.5 ng / ml ( 0 to 5 ) , and ca19 - 9 107.3 u / ml ( 0 to 36 ) . the endoscopy showed an intraluminal protruding lesion covered with normal mucosa along the anterior wall of the lower body , antrum , and duodenal bulb ( fig . a computed tomography of the abdomen showed about a 1012 cm exophytic mass at the antrum and lower body of the stomach , with invasion to the liver , pancreas , and transverse colon ( fig . 2 ) . eus with a radial endoscope ( ue 260 ; olympus , tokyo , japan ) was performed subsequently to assess the gastric wall and evaluate the characteristics of the mass . the eus showed a heterogeneous echogenic texture with multiple hyperechoic deposits and anechoic necrotic zones inside the large tumor mass that was thought to have developed in the fourth hypoechoic layer ( muscularis propria ) . however , the mucosal and submucosal layer were intact , and the extraluminal border could not be assessed due to the very large size of the mass ( fig . 3 ) . a non - operable malignant gastrointestinal stromal tumor ( gist ) was first suspected . therefore , eus - tcb with a linear endoscope ( uct240 ; olympus ) was performed for rapid pathology to confirm the clinical suspicion with immunohistochemical staining and to save costs . the signet ring tumor cells were immunoreactive for cytokeratin ( ck , 200 ) ( fig . 4 ) . chemotherapy with ts-1 ( ts - one ; jeil pharmaceutical co. , seoul , korea ) plus iv cisplatin ( cisplatin ; ildong pharmaceutical co. , seoul , korea ) was started . ts-1 was given orally at a dose of 40 mm / m twice daily for 2 weeks followed by a 1-week rest , and cisplatin was given intravenously on day 1 at a dose of 60 mg / m . during the admission , a percutaneous drainage ( pcd ) tube the general condition of the patient deteriorated rapidly after about 2 weeks from admission and the patient died 2 months after the diagnosis . this case report of a patient with gastric primary signet - ring cell carcinoma with features of gist was confirmed by eus - tcb . gastric cancers have various endoscopic findings , and histology is used to confirm the diagnosis.6 however , it is often difficult to confirm the histologic diagnosis despite taking a biopsy specimen , because the tumor surface of gastric cancers mimicking a submucosal tumor ( gcsmt ) is covered by normal mucosa.1 gcsmts are very rare ; they account for 0.1% to 0.63% of all resected gastric cancers.7 moreover , the histological confirmation of a signet ring cell type is uncommon . eus alone can provide useful information on gcsmts;8 however , it is difficult to determine the histological nature of the lesions from the eus image alone.9 the methods used to overcome this problem include eus - fna,2,3 eus - tcb , esmr,4 laparoscopic excision biopsy,10 and open surgery.5 however , the best method for confirmation of the diagnosis has not been established yet . for a definite diagnosis of a submucosal tumor , tissue acquisition , and pathology confirmation recently , mekky et al.11 reported that the results of eus - fna in 141 patients with gastric smts were diagnostic , suspicious , and nondiagnostic in 43.3% , 39% , and 17.7% of cases , respectively , with an overall accuracy of 95.6% and the accuracy of differentiating potentially malignant lesions of 94.2% . sftoiu et al.12 reported that the yield of adequate tissue sampling was similar for eus - fna and eus - tcb ( 96.4% vs. 89.3% , p = not significant ) . however , the accuracy for obtaining a specific diagnosis was significangly lower for the eus - fna compared to the eus - tcb ( 5.3% and 68.4% , p<0.005 ) . cantor et al.13 suggested that the esmr has a significantly higher diagnostic yield than jumbo forceps biopsy with the use of the bite - on - bite technique for the evaluation of subepithelial lesions limited to the submucosa . the diasgnositc yield of the jumbo forceps biopsy was four out of 23 cases ( 17% ) compared to 20 out of 23 cases ( 87% ) of the esmr ( p<0.001 ) . the esmr , however , accompanies major complications such as bleeding ( 0% to 24% ) and perforation ( 0% to 5% ) . therfore , the eus - tcb was performed in this case for rapid pathology in order to confirm the clinical suspicion with immunohistochemical staining , with a relatively lower complication rate . in conclusion , this is the first report of the eus - tcb used as a diagnostic tool in a case of gastric primary signet - ring cell carcinoma with features of gist . eus - tcb has low complication rate and enables immunohistochemical staining unlike other methods such as eus - fna , esmr , or open surgery , which is why it should be considered when results of a mucosal biopsy are not diagnostic . the possibility of signet ring cell carcinoma , which has a poor prognosis , should always be considered even in cases with gcsmt developing in the fourth gastric layer .
a submucosal gastric adenocarcinoma , especially the signet ring cell type , is rare . 
 the histologic evaluation techniques for this lesion has not been established ; however , histologic confirmation is very important for decision of treatment method . here , 
 we report a 57-year - old man with a 12-cm gastric submucosal signet ring cell type adenocarcinoma , diagnosed by an endoscopic ultrasound - guided trucut biopsy and immunochemical studies . 
 this case suggests that the endoscopic ultrasound - guided trucut biopsy might be a useful diagnostic method in cases of gastric adenocarcinoma with features of gastrointestinal stromal tumor .