in spite of the relatively high accuracy of endoscopic ultrasound - assisted fine - needle aspiration ( eus - fna ) in diagnosing lymphomas , inadequate sampling by eus - fna often makes it difficult to perform immunohistochemical analysis , thus limiting its application in the classification of lymphoma . natural orifice transluminal endoscopic surgery ( notes ) is a surgical technique by which procedures such as exploration , biopsy , organ resection , and anastomosis can be performed using an endoscope passed through a natural orifice [ such as the mouth , stomach , colon ( or rectum ) , vagina , bladder , or esophagus ] and then entered into the abdominal cavity , mediastinum , or thoracic cavity through an internal incision . the advantages of notes include reduced trauma , faster recovery , absence of scarring , and painlessness , and such procedures have been regarded as third - generation surgery . here we report an eus - assisted retroperitoneal lymph node biopsy performed in a patient who had developed enlarged retroperitoneal lymph nodes with an unknown cause . this procedure was carried out on november 10 , 2014 , after obtaining the approval of the ethics committee and informed consent documents signed by the patient . a 60-year - old male patient was admitted to our hospital complaining of epigastric discomfort , which had persisted for 1 month . a computerized tomography ( ct ) scan suggested the presence of multiple soft - tissue density masses in the patient 's abdominal cavity , the largest of which was 7.7 cm  7.2 cm [ figure 1a and b ] . positron emission tomography - ct ( pet - ct ) showed that these masses had abnormal f - fdg uptake [ figure 2a and b ] . the patient then underwent eus examination ; multiple enlarged retroperitoneal lymph nodes were found between the body of the pancreas and the gastric wall . we then performed eus - fna [ figure 3 ] to obtain a tissue sample for biopsy . pathological examination revealed only a few heterotypic cells [ figure 4 ] . because of the lack of definite pathological evidence , diagnosis of the patient 's condition was extremely difficult . ct scan showing multiple , enlarged soft tissue - density images in the abdominal cavity pet - ct showing the accumulation o f abnormal radioactivity in soft tissue - density images in the abdominal cavity eus - fna of a lymph node eus - fna showing a few heterotypic cells to obtain adequate tissue samples of the enlarged lymph nodes for immunohistochemical analysis , we performed eus - assisted retroperitoneal lymph node biopsy . a standard single - channel gastroscope ( epk - i , pentax , tokyo , japan ) was used throughout the endoscopic procedure ; a linear array ultrasonic endoscope ( eg3830ur ; pentax precision instrument corporation , orangeburg , ny , usa ) was used to evaluate the size of the lymph nodes , their echo characteristics , and localization . a triangle - tip knife and an insulated - tip ( it ) knife ( both from olympus corporation , tokyo , japan ) were used for resection of the gastric wall and enucleation of the lymph node . a pair of hot forceps ( fd-410lr , olympus corporation , tokyo , japan ) was used for gastric wall hemostasis . adequate preoperative communication with the patient and his family was performed and associated issues including the necessity , feasibility , safety , and probable complications of the operation were explained thoroughly . for the procedure , the patient was placed in a supine position and he received standard intravenous anesthesia with propofol . the site nearest to the retroperitoneal lymph nodes in the posterior wall of the gastric body was chosen for puncture . a methylthioninium chloride and saline compound solution was injected into the puncture channel for labeling when the needle was retrieved . the lymph node was also marked by a triangle tip knife with the cautery under eus - guidance . then , the ultrasound transducer was pulled out ; therapeutic gastroscopy with a transparent cap was then performed . a triangle - tip knife was used to incise the full thickness of the gastric wall along the labeled site . the triangle - tip knife was used to separate the tissues surrounding the stomach wall sufficiently until the targeted lymph node capsule was exposed . then , enucleation of the targeted lymph node was performed using an it knife [ figure 5 ] . after tissue samples were obtained , the hot forceps were used to stop the bleeding . the endoscope was retrieved from the stomach and the procedure was completed by closing the incision in the stomach wall using metal clips [ video 1 ] . the results showed : cd3(large cell- ) ; vimentin(+ ) ; pax-5(- ) ; cd15(- ) ; cd20(large cell+ ) ; cd21(+ ) ; ki-67(large cell8%+ ) ; cd30(- ) ; cd68(partly+ ) ; ck(- ) ; mum-1(- ) ; cd10(- ) ; bcl-6(+ ) ; bcl-2(+ ) . the diagnosis was : non - hodgkin lymphoma , germinal center b - cell - like diffuse large b - cell lymphoma [ figure 6 ] . ( a ) the gastroscope entered into the abdominal cavity after incision of the full thickness of the gastric wall . the prelabeled lymph node was found , ( b ) the removed lymph node tissues immunohistochemical staining : cd3(large cell- ) ; vimentin(+ ) ; pax-5(- ) ; cd15(- ) ; cd20(large cell+ ) ; cd21(+ ) ; ki-67(large cell8%+ ) ; cd30(- ) ; cd68(partly+ ) ; ck(- ) ; mum-1(- ) ; cd10(- ) ; bcl-6(+ ) ; bcl-2(+ ) . the diagnosis was non - hodgkin lymphoma , germinal center b - cell - like diffuse large b - cell lymphoma the patient was given standard postoperative treatments and nursing care including ecg monitoring , ceftazidime as prophylaxis against infection , proton pump inhibitors , and nutritional support . the patient 's highest temperature after the procedure was 37.2c and he only felt mild epigastralgia . the blood test results after the procedure were : white blood cell ( wbc ) count 12.8  10/l and percentage of neutrophils 80.3% . the wbc count decreased to 6.5  10/l and the percentage of neutrophils decreased to 61.8% , 4 days after the procedure . the patient gradually returned to a normal diet and normal physical activities by 3 days after the procedure . the patient was then transferred to the department of hematology to undergo further therapy . the r - chop regimen ( pathological evidence is an indispensable part of the diagnosis and differential diagnosis of lymphoma and is significant for the classification of lymphomas . precise pathological classification is critical for the choice of chemotherapeutic regimen in cases of lymphoma . in the early 1990s , eus - fna was first used for tissue biopsy of tumors around the gastrointestinal tract . in spite of its high accuracy , the lack of sufficient tissue material obtained using this technique often renders immunohistochemical staining inconclusive and limits its application in the classification of lymphomas . how to obtain an adequate sample that can be used for immunohistochemical testing is a primary problem in need of a solution . in a study by mohamad et al . , the results of eus - fna of two patients who had suspected lymphoma were negative . however , positive results were obtained by use of eus - guided trucut biopsy ( eus - tcb ) . the authors suggested that the use of eus - tcb with 19 g needle could permit more tissue materials to be obtained in those who had a negative eus - fna result . this minimally invasive procedure can be used for the preoperative diagnoses of some difficult cases . analyzed and compared the efficacies of eus - fna and eus - tcb in the diagnosis and classification of lymphoma . among the 24 included patients , 23 patients underwent eus - fna . only one patient received eus - tcb alone , while the other 22 patients received both eus - fna and eus - tcb . the results showed that the accurate diagnostic rate of eus - guided biopsy was 79% ( 19/24 ) and the accurate rate of eus - guided biopsy for classification was just 66.6% ( 16/24 ) . this indicated that eus - guided biopsy was of limited value in the classification of lymphoma . there have been more than 300 reports of notes clinical applications from around the world . over 50 cases of cholecystostomy and endectomy by transvaginal notes have been performed in germany , and 116 notes surgeries ( including 77 transgastric cholecystotomy cases ) have been reported in brazil . however , there are few case reports regarding the clinical application of notes in china . wang et al . presented a case of laparoscopy - assisted transgastric endoscopic biopsy of a retroperitoneal lymph node . in this case , an endoscopic full - thickness resection ( eftr ) with the aid of laparoscopy was used to extirpate an enlarged retroperitoneal lymph node . pathological and immunohistochemical tests confirmed the diagnosis of retroperitoneal b - cell lymphoma ( diffuse large b - cell lymphoma ) . in recent years , these studies showed that eus was very useful for creating transgastric access and locating the targets . in this study , we successfully used eus - assisted notes to perform enucleation of a retroperitoneal enlarged lymph node without laparoscopic assistance . the use of a minimally invasive procedure not only enables more tissue materials to be obtained but also causes less trauma than a laparoscopy - assisted approach . in this patient , blood test results recovered to normal levels by 4 days after the procedure and the highest postoperative body temperature was just 37.2c . he was also able to return to a normal diet 3 days after the procedure . our experience suggests that this is an alternative and minimally invasive approach for the biopsy of retroperitoneal lymph nodes .
since its introduction in the early 1990s , endoscopic ultrasound - assisted fine - needle aspiration ( eus - fna ) has been used for sampling of extraintestinal mass lesions and peri - intestinal lymphadenopathy . 
 although eus - fna is highly accurate , lymphomas can be challenging to diagnose using eus - fna . 
 we present the case of a 60-year - old male who had experienced upper abdominal discomfort for 1 month . 
 computerized tomography ( ct ) examination revealed multiple soft - tissue shadows located above the pancreatic body . 
 the biggest shadow had a cross - sectional area of 7.7 cm  7.2 cm . 
 positron emission tomography - ct ( pet - ct ) imaging showed increased uptake of 18f - fdg by these soft - tissue shadows . to investigate further , 
 eus was performed and it revealed the presence of multiple hypoechoic round lymph nodes . during the procedure , 
 eus - fna was performed , but only a few dyskaryotic cells were observed by cytological evaluation . 
 eus - assisted retroperitoneoscopy and lymph node biopsy were performed to obtain more tissue for immunohistochemical analysis and subclassification of lymphoma . 
 finally , the patient was diagnosed with non - hodgkin lymphoma , germinal center b - cell - like diffuse large b - cell lymphoma by this technique . 
 eus - assisted transendoscopic retroperitoneal lymph node biopsy is an alternative procedure for the diagnosis of lymphomas .