Appropriate endoscopic treatment selection and surveillance for superficial non-ampullary duodenal epithelial tumors.

OBJECTIVES: Superficial nonampullary duodenal epithelial tumors (SNADETs) have become frequently detected and referred for endoscopic resection (ER). However, optimal treatment methods and long-term outcomes after ER of SNADETs have not been fully elucidated. We aimed to clarify them by analyzing our large cohort of patients with SNADETs. MATERIALS AND METHODS: We enrolled 190 consecutive tumors from 189 patients undergoing ER between January 2004 and September 2019. Cases were stratified into endoscopic submucosal dissection (ESD), conventional endoscopic mucosal resection, (CEMR) and underwater endoscopic mucosal resection (UEMR). Baseline characteristics and short-term outcomes were compared between the groups. Long-term outcomes were also investigated with a median follow-up of 36 months. RESULTS: ESD significantly exceeded CEMR (96.4% vs. 52.9%; p = .0026) and UEMR (96.4% vs. 50.0%; p = .0008) in complete resection rates for 11- to 20-mm lesions; the differences were not significant for lesions ≤10 mm. Local recurrence only occurred in patients with an incomplete resection. Only patients with submucosal invasion died from the primary neoplasms. The 3- and 5-year disease-free survivals were 91.3% and 83.5%. CONCLUSIONS: While tumors ≤10 mm seem to be good indications for endoscopic mucosal resection, ESD should be considered for larger tumors to better achieve complete resection. Patients with submucosal invasive carcinomas have a great risk of cancer death. Therefore, a close follow-up and an additional treatment are desirable.

An endoscopic treatment strategy for superficial tumors in patients with ulcerative colitis.

BACKGROUND AND AIM: Endoscopic resection is feasible for superficial tumors in patients with ulcerative colitis; however, endoscopic resection options have not been evaluated comprehensively. We evaluated the efficacy and safety of endoscopic submucosal dissection and endoscopic mucosal resection, and decision making regarding endoscopic resection options for patients with ulcerative colitis. METHODS: Endoscopically treated tumors from patients with ulcerative colitis were analyzed retrospectively. We evaluated en bloc and R0 resection, adverse events, local tumor recurrence, and metachronous lesion occurrence rates. RESULTS: We examined 102 tumors (mean size, 12 mm; non-polypoid, 55 tumors) from 74 patients with ulcerative colitis, of whom, 39 and 63 underwent endoscopic submucosal dissection and endoscopic mucosal resection, respectively. The R0 resection rate was significantly higher for endoscopic submucosal dissection (97%) than for endoscopic mucosal resection (80%) (P = 0.0015). For 11-20-mm tumors, the R0 resection rate was significantly higher for endoscopic submucosal dissection (94%) than for endoscopic mucosal resection (55%) (P = 0.0027); the endoscopic submucosal dissection and endoscopic mucosal resection R0 rates did not differ for ≤ 10-mm tumors. The non-polypoid tumor R0 resection rates were significantly higher for endoscopic submucosal dissection (100%) than for endoscopic mucosal resection (65%) (P < 0.001) and did not differ regarding the polypoid tumor R0 resection rates (75% vs 86%, P = 0.49). Four patients experienced intraoperative perforation during endoscopic submucosal dissection. No local recurrences occurred. Metachronous high-grade dysplasia occurred in three patients during surveillance. CONCLUSIONS: In patients with ulcerative colitis, endoscopic submucosal dissection is suitable for ≥ 11-mm and non-polypoid tumors, whereas endoscopic mucosal resection is acceptable for ≤ 10-mm tumors.

Factors influencing interruption of colorectal endoscopic submucosal dissection.

BACKGROUND AND AIMS: Although colorectal endoscopic submucosal dissection (ESD) has become a standardized procedure worldwide, the difficulty of the procedure is well known. However, there have been no studies assessing the causes of treatment interruption. The present study aimed to evaluate the factors involved in the interruption of colorectal ESD. METHODS: We retrospectively analyzed 1116 consecutive superficial colorectal neoplasms of 1012 patients who were treated with ESD between August 2008 and September 2018. The clinicopathological characteristics and treatment outcomes were analyzed. RESULTS: Interrupted ESD was reported in 14 lesions (1.3%) of the total study population. Univariate analysis of clinical characteristics indicated that age, 0-I macroscopic-type tumor, and tumor location on the left side colon were risk factors for interruption. Multivariate analysis revealed that 0-I macroscopic-type tumor was the sole preoperative independent risk factor for interruption. Univariate analysis revealed that the presence of muscle-retracting sign (MRS), deep submucosal tumor invasion, and intermediate invasive growth pattern represented the etiology of interruption. Multivariate analysis indicated that MRS can be a sole key sign for the interruption. Additionally, the resectability and curability of 0-I type tumors were significantly inferior to those of predominantly lateral spreading tumors. Observations of 0-I macroscopic-type tumors, MRS, and submucosal deep invasion were significantly more frequent in interrupted cases. Conventional endoscopic images without magnification endoscopy were more associated with interruption than irregular surfaces or Vi pit patterns in cases with 0-I type tumors. CONCLUSION: ESD of 0-I type tumors is highly disruptive, and undiagnosable submucosal infiltration can reduce the curability.

Utility of multi-detector computed tomography scans after colorectal endoscopic submucosal dissection: a prospective study.

BACKGROUND AND AIMS: Several reports have described major adverse events after endoscopic submucosal dissection (ESD), such as perforation or bleeding. However, few studies have discussed the occurrence of post-ESD electrocoagulation syndrome (PEECS) after colorectal ESD. In addition, the occurrence of fever without abdominal pain in patients requires postoperative management similar to that required for PEECS. Therefore, we have defined post-ESD inflammatory syndrome (PEIS) composed of both PEECS and fever without abdominal pain. This study aimed to evaluate the correlation between the findings of multi-detector computed tomography (MDCT) imaging and PEIS in patients. METHODS: Between January 2015 and October 2015, we performed colorectal ESD in 100 patients; after this, all patients underwent abdominal examinations by MDCT scans. Nine patients who experienced intraoperative perforations or penetrations were excluded; 91 patients were enrolled in our prospective study. MDCT findings in patients were classified according to the amount of extraluminal gas. The patients were divided into 2 groups based on the presence or absence of extraluminal gas and were assessed for co-occurring PEIS. RESULTS: Among the 91 patients, extraluminal gas was observed in 31 (34%); of these, PEIS occurred in 14 (15%) patients. Patients with extraluminal gas had increased incidence of PEIS compared with patients without extraluminal gas (29% vs 8%, P = .014). CONCLUSIONS: Extraluminal gas was detected by MDCT in many cases and significantly correlated with the occurrence of PEIS, even in cases without obvious intraoperative perforation or penetration. MDCT findings after ESD may be useful for predicting PEIS and appropriate perioperative management.

Histological verification of the usefulness of magnifying endoscopy with narrow-band imaging for horizontal margin diagnosis of differentiated-type early gastric cancers.

BACKGROUND: Although magnifying endoscopy with narrow-band imaging (ME-NBI) can help identify the horizontal margin (HM) of early gastric cancer (EGC), little is known about the factors that can clarify the HM by using ME-NBI. We aimed to characterize the pathological features of lesions in which the HM was identified using ME-NBI. METHODS: The HMs of 639 differentiated-type EGCs treated with endoscopic submucosal dissection or surgery were analyzed using conventional endoscopy and ME-NBI. The number and width of the intervening parts (IP) and the number, width, and depth of the subepithelial capillaries (SEC) in cancerous and noncancerous areas were measured. RESULTS: In 13 lesions (2.0%), more than 90% of the HM was not recognized with conventional endoscopy, but 11 of these lesions were detectable with ME-NBI (NBI group). The HMs of the other 626 lesions were mostly recognized using conventional endoscopy (WLI/CE group). In the NBI group, the IP width, standard deviation (SD), and number of IPs did not significantly differ between the cancerous and noncancerous areas. However, the SEC number was significantly larger and the depth was shallower in cancerous areas. In the WLI/CE group, the IP width and SD were significantly larger, but the IP number was significantly smaller in cancerous areas. The SEC depth was significantly shallower in cancerous areas. CONCLUSIONS: Differences of IP width, SD, and IP number may be factors for identifying HMs with conventional endoscopy. Because NBI can better visualize vessel structures, the increased SEC number and shallow SECs may clarify the HM.

A pilot study of fluorescent imaging of colorectal tumors using a γ-glutamyl-transpeptidase-activatable fluorescent probe.

UNLABELLED: Backgrounds/Aim: Colorectal laterally spreading tumors (LSTs) are sometimes difficult to visualize even with image-enhanced endoscopy. γ-Glutamyl-transpeptidase (GGT) is a cell surface-associated enzyme that is overexpressed in various types of human cancers. Furthermore, GGT expression is higher in colorectal cancer cells than in normal colorectal mucosa. γ-Glutamyl hydroxymethyl rhodamine green (gGlu-HMRG), an activatable fluorescent probe, is nonfluorescent under a neutral pH and normal cellular environment; however, it turns highly fluorescent upon reaction with GGT. We evaluated ex vivo fluorescent imaging of colorectal LSTs using this GGT-activatable fluorescent probe. METHODS: Between March 2013 and March 2014, 30 endoscopically resected colorectal LSTs were prospectively included in this study. Each was analyzed by first taking a baseline image before spraying, then spraying with gGlu-HMRG onto the freshly resected specimen, and finally taking fluorescent images 15 min after spraying with a dedicated imaging machine. RESULTS: Of the LSTs, 67% rapidly showed positive fluorescent activity. These activities were shown in adenoma (54%) and carcinoma in adenoma (76%), and in LST-granular type (80%) and LST-nongranular type (40%). CONCLUSION: Topically spraying gGlu-HMRG enabled rapid and selective fluorescent imaging of colorectal tumors owing to the upregulated GGT activity in cancer cells.

Short-term outcomes of colorectal endoscopic submucosal dissection performed by trainees.

BACKGROUND: Colorectal endoscopic submucosal dissection (ESD) is a relatively new therapy that has been accepted as the most effective treatment procedure for superficial colorectal neoplasms. Given the increasing acceptance and use of this procedure worldwide, the outcomes of colorectal ESD performed by trainees should be understood from a practical perspective and for developing strategies to introduce ESD to trainees. This study aimed to evaluate the clinical outcomes of ESD when conducted by less-experienced endoscopists. SUMMARY: We retrospectively reviewed the clinical outcomes of 164 patients with 164 colorectal neoplasms who underwent ESD carried out by 20 trainees performing their first colorectal ESDs between April 2005 and March 2012. For each operator, clinical data were collected between the first and 30th cases. For evaluating the technical aspects of the ESD procedure, the endoscopic characteristics of the lesions, procedure time, en bloc resection rate, R0 resection rate, invasion depth and complications were evaluated. The median procedure time was 95 min; about 75% of the lesions were resected within 120 min. Apparent perforation or electric damage in the muscularis propria was seen in 4% of lesions. In terms of factors with the potential to effect procedure time, lesion size and pathological invasion depth were significantly different between shorter and longer treatment times for granular-type laterally spreading tumors (LST). KEY MESSAGES: A granular-type LST of <40 mm is a good lesion for introducing colorectal ESD to trainees. Trainees should have a strong ability to make a depth diagnosis before starting ESD.

A suspected case of serum IgG4-negative type 1 autoimmune pancreatitis detected due to localized pancreatic duct narrowing: a case report.

A 50-year-old woman was referred to our hospital with elevated serum amylase levels. Physical examination revealed no jaundice or abdominal tenderness. Serum IgG4 was negative. Computed tomography revealed a localized pancreatic duct narrowing in the pancreatic head, with caudal pancreatic duct dilation and an intraductal papillary mucinous neoplasm. Pancreatic enlargement was not observed. Endoscopic ultrasonography (EUS) showed a small hypoechoic mass. Although EUS-guided, fine-needle aspiration was performed, no diagnosis was established. Endoscopic retrograde pancreatography showed a localized narrowing in the main pancreatic duct of the pancreatic head. A biopsy of the narrowing was performed through the minor papilla because of difficult access from the major papilla. The specimen showed the infiltration of numerous IgG4-positive plasma cells, suggesting type 1 autoimmune pancreatitis (AIP). Six months later, magnetic resonance cholangiopancreatography revealed improvement in the narrowing without specific treatment. The patient presented with localized narrowing of the pancreatic duct and caudal duct dilation, which was distinct from pancreatic cancer. Diagnostic difficulties arose from negative serum IgG4 results, the lack of typical imaging characteristics of AIP, and failure to meet the AIP criteria according to the relevant Japanese and international guidelines. However, AIP was suspected and surgery was successfully avoided through a biopsy.

Systemic AL amyloidosis with multiple submucosal hematomas of the colon: a case report and literature review.

Amyloid light-chain (AL) amyloidosis rarely causes colorectal submucosal hematoma. A 76-year-old man presented with a complaint of bloody stool. An initial colonoscopy revealed ulcerative lesions in the descending colon, leading to a diagnosis of ischemic colitis. One month later, he presented with cardiac failure, suspected cardiac amyloidosis, and underwent a second colonoscopy. Although it revealed multiple ulcerative lesions from the ascending to transverse colon, biopsy samples did not confirm amyloid deposition. He underwent a third colonoscopy 3 weeks later due to recurrent bloody stool. It showed multiple submucosal hematomas from the ascending to descending colon concomitant with ulcerative lesions in the descending colon and multiple elevated lesions in the sigmoid colon. Biopsy samples confirmed amyloid deposition. Using a systemic search, multiple myeloma with AL amyloidosis was diagnosed. Colorectal submucosal or intramural hematomas are conditions usually encountered in trauma, antithrombotic use, or coagulation disorders. Based on our review of the literatures, we identified several differences between colorectal intramural hematoma caused by amyloidosis and those caused by other etiologies. We believe that amyloidosis should be considered when relatively small and multiple colorectal hematomas, not restricted to the sigmoid colon, and with concomitant findings of erosions and ulcers, are observed.

Difficulty in the diagnosis of pancreatic cancer based on the initial CT report: A retrospective study.

The role of computed tomography (CT) in the initial diagnosis of pancreatic cancer (PC) is well-known. CT reports made by radiologists are important as not all patients with PC are examined by specialists; however, some cases are not identified based on CT reports. Diagnosis via imaging of PC is sometimes difficult, and the diagnostic rate of PC and other pancreatic diseases can vary across radiologists. This study aimed to examine the diagnostic rate of PC in initial CT reports and the details of cases with diagnostic difficulties. This single-centered, retrospective study collected clinical data of 198 patients with histologically diagnosed PC between January 2018 and April 2022. Out of these contrast-enhanced CT was performed in 192 cases. PC was not reported as the main diagnosis in 18 patients (9.4%; 11 men and 7 women). Among these 18 cases, intrapancreatic mass lesions were detected in 3 (1.6%), indirect findings such as bile/pancreatic duct stenosis or dilation were detected in 5 (2.6%), and no PC-related findings were found in 10 (5.2%). The specialists suspected PC in 15 of these 18 cases based on initial CT reports. 17 cases were confirmed by endoscopic ultrasound-fine needle aspiration and one by biopsy after upper gastrointestinal endoscopy. To improve accuracy of its diagnosis, it is important that specialists provide feedback to diagnostic radiologists regarding the findings they did not report. Endoscopic ultrasound-fine needle aspiration should be performed by specialists when there is clinical information which indicates pancreatic disease of any kind.

Giant Brunner's gland hyperplasia of the duodenum successfully resected en bloc by endoscopic mucosal resection: A case report.

BACKGROUND: Duodenal Brunner's gland hyperplasia (BGH) is a therapeutic target when complications such as bleeding or gastrointestinal obstruction occur or when malignancy cannot be ruled out. Herein, we present a case of large BGH treated with endoscopic mucosal resection (EMR). CASE SUMMARY: An 83-year-old woman presented at our hospital with dizziness. Blood tests revealed severe anemia, esophagogastroduodenoscopy showed a 6.5 cm lesion protruding from the anterior wall of the duodenal bulb, and biopsy revealed the presence of glandular epithelium. Endoscopic ultrasonography (EUS) demonstrated relatively high echogenicity with a cystic component. The muscularis propria was slightly elevated at the base of the lesion. EMR was performed without complications. The formalin-fixed lesion size was 6 cm × 3.5 cm × 3 cm, showing nodular proliferation of non-dysplastic Brunner's glands compartmentalized by fibrous septa, confirming the diagnosis of BGH. Reports of EMR or hot snare polypectomy are rare for duodenal BGH > 6 cm. In this case, the choice of EMR was made by obtaining information on the base of the lesion as well as on the internal characteristics through EUS. CONCLUSION: Large duodenal lesions with good endoscopic maneuverability and no evident muscular layer involvement on EUS may be resectable via EMR.

Antimicrobial therapy outcomes in acute cholangitis: Hilar multiple obstructions versus single hilar and common bile duct obstructions.

Background and Aim: The appropriate duration of antimicrobial therapy for acute cholangitis (AC) arising from multiple hilar biliary obstructions as opposed to simple obstruction in the extrahepatic bile duct has not been established. This study assessed the efficacy of the duration of antimicrobial treatments in the Tokyo Guidelines 2018 for AC based on the cause and site of obstruction. Methods: This single-center retrospective study involved patients with AC who underwent successful biliary drainage and completed a 7-day or shorter antimicrobial treatment. Patients were categorized into three groups: Group 1, bile duct stone or benign obstruction; Group 2, simple biliary obstruction due to malignancy; and Group 3, multiple hilar biliary obstruction due to malignancy. The primary outcome was clinical cure rate, and the secondary outcomes were 3-month recurrence rate and length of hospital stay. Results: A total of 373 patients were selected. Patients in Group 3 were younger or had Charlson Comorbidity Index ≥4, and had fewer positive blood cultures. In Group 3, the clinical cure rate (87.1%) and 3-month recurrence rate (32.3%) were less favorable than those in the other groups. In Group 1, the clinical cure rate was significantly higher (98.1%, P = 0.02) with a much lower 3-month recurrence rate of only 3.4% (P < 0.001) than that in the other groups. The median hospital stay for all groups was 7 days. Conclusion: This study suggests that the outcomes in Group 3 may be worse than those in Groups 1 or 2, regardless of the duration of the antibiotic treatment.

Association of short-course antimicrobial therapy and bacterial resistance in acute cholangitis: Retrospective cohort study.

Background and study aims Although the number of resistant bacteria tends to increase with prolonged antimicrobial therapy, no studies have examined the relationship between the duration of antimicrobial therapy and increase in the number of resistant bacteria in acute cholangitis. We hypothesized that the short-term administration of antimicrobial agents in acute cholangitis would suppress bacterial resistance. Patients and methods This was a single-center, retrospective, observational study of patients with acute cholangitis admitted between January 2018 and June 2020 who met the following criteria: successful biliary drainage, positive blood or bile cultures, bacteria identified from cultures sensitive to antimicrobials, and subsequent cholangitis recurrence by January 2022. The patients were divided into two groups: those whose causative organisms at the time of recurrence became resistant to the antimicrobial agents used at the time of initial admission (resistant group) and those who remained susceptible (susceptible group). Multivariate analysis was used to examine risk factors associated with the development of resistant pathogens. Multivariate analysis investigated antibiotics used with the length of 3 days or shorter after endoscopic retrograde cholangiopancreatography (ERCP) and previously reported risk factors for the development of bacterial resistance. Results In total, 89 eligible patients were included in this study. There were no significant differences in patient background or ERCP findings between the groups. The use of antibiotics, completed within 3 days after ERCP, was associated with a lower risk of developing bacterial resistance (odds ratio, 0.17; 95% confidence interval, 0.04-0.65; P =0.01). Conclusions In acute cholangitis, the administration of antimicrobials within 3 days of ERCP may suppress the development of resistant bacteria.

Efficacy of Short-Course Antibiotic Therapy for Acute Cholangitis With Positive Blood Cultures: A Retrospective Study.

BACKGROUND: Short-term treatment of acute cholangitis is sufficient for cure compared with the standard treatment duration. Whether this short-course antimicrobial therapy is effective in patients with acute cholangitis with positive blood cultures has not been fully investigated. This study assessed whether patients with acute cholangitis could achieve successful outcomes with a three-day or shorter antimicrobial treatment period, even with a positive blood culture. METHODS: This single-center retrospective study involved patients with acute cholangitis, defined according to the Tokyo Guidelines 2018 for any cause, who underwent successful biliary drainage and completed a seven-day or shorter antimicrobial treatment. Patients were categorized into six groups based on the duration of antibiotic use (short or standard) after endoscopic retrograde cholangiopancreatography and blood culture findings (positive, negative, or no collection). The primary outcome was the clinical cure rate, defined as no initial presenting symptoms by day 14 after biliary drainage and no recurrence or death by day 30. Secondary outcomes included a three-month recurrence rate and length of hospital stay. RESULTS: In total, 389 cases were selected, and 27 patients (6.9%) undergoing short-course therapy tested positive for blood culture. The clinical cure rate (n=25, 92.6%) in this group was comparable to that in the other groups. For the three-month recurrence rate (n=1, 3.7%) and median hospital stay (six days), this group's outcomes were either better or similar to those of the other groups. CONCLUSIONS: For cases of successful drainage in acute cholangitis, even with positive blood cultures, short-term antibiotic therapy may be appropriate.

Endoscopic submucosal dissection for early gastric cancer in the remnant stomach after gastrectomy.

BACKGROUND: Endoscopic submucosal dissection (ESD) for early gastric cancer (EGC) after surgical gastrectomy is a technically difficult procedure because of the limited working space in the remnant stomach as well as the presence of severe gastric fibrosis and staples under the suture line. OBJECTIVE: We evaluated clinical results including long-term outcomes to determine the feasibility and effectiveness of ESD for EGC in the remnant stomach of patients after gastrectomy. DESIGN: Retrospective study. SETTING: National Cancer Center Hospital, Tokyo, Japan. PATIENTS: We investigated patients undergoing ESD for EGC in the remnant stomach from 1997 to 2011. INTERVENTION ESD MAIN OUTCOME MEASUREMENTS: We examined the patient characteristics, endoscopic findings, technical results, adverse events, and histopathologic results including curability and evaluations of Helicobacter pylori gastritis in addition to the rates of local recurrence, metachronous gastric cancer, overall survival, and cause-specific survival. RESULTS: A total of 128 consecutive patients with 139 lesions had previously undergone 87 distal (68%), 25 proximal (19.5%) and 16 pylorus-preserving gastrectomies (12.5%). The median period from the original gastrectomy to the subsequent ESD for EGC in the remnant stomach was 5.7 years (range 0.6-51 years), the median tumor size was 13 mm (range 1-60 mm), and the median procedure time was 60 minutes (range 15-310 minutes). There were 131 en bloc resections (94%), with curative resections achieved for 109 lesions (78%); 22 lesions (16%) resulted in non-curative resections, and 8 lesions (6%) had only a horizontal margin positive or had inconclusive results. A total of 118 patients (92%) were assessed as H pylori gastritis-positive, with 7 patients (5%) negative. Adverse events included 2 cases of delayed bleeding (1.4%) and 2 perforations (1.4%), with 1 patient requiring emergency surgery. The 5-year overall and cause-specific survival rates were 87.3% and 100%, respectively, during a median follow-up period of 4.5 years (range 0-13.7 years), with no deaths from EGC in the remnant stomach. LIMITATIONS: Single-center, retrospective study. CONCLUSION: ESD for EGC in the remnant stomach of patients after gastrectomy was a feasible and effective therapeutic method and should become the standard treatment in such cases, based on the favorable long-term outcomes.

Acute liver failure due to herpes simplex viral hepatitis diagnosed by skin lesions and blood tests: a case report.

BACKGROUND: The incidence of acute liver failure from herpes simplex virus is rare. CASE PRESENTATION: A 71-year-old Japanese man was diagnosed with acute liver failure and was transferred to our hospital. Steroid therapy, plasma exchange, and hemodiafiltration were started for liver failure, and antimicrobial therapy was initiated for pneumonia. Staphylococcus epidermidis was detected in blood culture. Skin rash appeared; a positive anti-herpes simplex virus result led to the diagnosis of acute liver failure from herpes simplex virus. Hence, acyclovir was started. After blood tests improved, treatments for acute liver failure were discontinued. Antimicrobial therapy was continued; however, he died. In this case, persistent bacteremia and drug-induced liver damage due to acyclovir may have contributed to his death. CONCLUSIONS: Acute liver failure can lead to complications and death. Thus, careful observation is crucial, even if the patient has shown some improvements.

Spontaneous retroperitoneal hematoma with duodenal obstruction with diagnostic use of endoscopic ultrasound: A case series and literature review.

Spontaneous retroperitoneal hematoma is rare and can cause duodenal obstruction. We report four cases of spontaneous retroperitoneal hematoma with duodenal obstruction, wherein endoscopic ultrasound was useful for diagnosis. The patients complained of vomiting with stable vital signs. Computed tomography, esophagogastroduodenoscopy, and endoscopic ultrasound findings were similar in all cases. Contrast-enhanced computed tomography revealed a low-density mass around the 2nd to 3rd part of the duodenum. Esophagogastroduodenoscopy showed an edematous, reddish, but non-neoplastic duodenal mucosa with stenosis of the lumen. Endoscopic ultrasound revealed a low-echoic mass around the duodenum and high-echoic floating matter suggesting debris and anechoic areas that indicated a liquid component. These findings suggested hematomas or abscesses. Although pseudoaneurysm of the pancreaticoduodenal artery was suspected in Case 3, we chose conservative treatment because the aneurysm was small. In Case 4, median arcuate ligament syndrome was suspected on angiography. No aneurysms or arteriovenous malformations were found; thus, endovascular embolization was not performed. The patients were treated conservatively and discharged within 3-5 weeks. English literature queries on spontaneous retroperitoneal hematoma with duodenal obstruction in MEDLINE revealed 21 cases in 18 studies. The clinical features of these patients and the present four cases have been discussed.