Joon Hyuk Choi

Asan Medical Center, Sŏul, Seoul, South Korea

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Publications (55)73.2 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Background and study aim: Endoscopic ultrasonography-guided transmural gallbladder drainage (EUS-GBD) has been proposed for the management of acute cholecystitis in high risk patients; however, little is known about the long-term outcomes of this treatment. The aim of this study was to evaluate the procedural and long-term outcomes of EUS-GBD with self-expandable metallic stent (SEMS). Patients and methods: Data for this retrospective study were obtained from a prospectively collected EUS database. Patients with acute cholecystitis who were deemed unsuitable for cholecystectomy were included. Study outcomes were technical and clinical success, adverse events, and stent patency. Results: EUS-GBD was technically and clinically successful in 62/63 patients (98.4 %; 95 % confidence interval [CI] 94.9 % - 100 %). Procedural adverse events included duodenal perforation (n = 1, 1.6 %) and self-limiting pneumoperitoneum (n = 2, 3.2 %), all of which resolved with conservative treatment. Long-term outcomes of EUS-GBD were evaluated in 56 patients who were followed for a median of 275 days (range 40 - 1185 days). Late adverse events developed in four patients (7.1 %; 95 %CI 5.7 % - 8.4 %), including asymptomatic distal stent migration (n = 2), and acute cholecystitis due to stent occlusion (n = 2). Two patients with occluded stent were successfully treated endoscopically (reintervention rate of 3.6 %). A total of 54 patients (96.4 %) had no recurrence of acute cholecystitis during follow-up. Median stent patency time was 190 days overall (range 15 - 1185 days) and 458 days (range 151 - 1185 days) for the 28 patients who were alive at the study end. The cumulative stent patency rate was 86 % at 3 years. Conclusions: EUS-GBD with an SEMS for acute cholecystitis showed excellent long-term outcomes and may be a definitive treatment in patients who are unsuitable for cholecystectomy because of advanced malignancy or high surgical risk.
    Endoscopy 06/2014; · 5.74 Impact Factor
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    ABSTRACT: To evaluate the success rates, procedural time and adverse event rates of the modified methods in endoscopic ultrasonography-guided hepaticogastrostomy (EUS-HGS). Twenty-eight patients in a prospective case series who underwent EUS-HGS (phase I). Forty-six patients in a matched case-control study (phase II). The simplified technique for fistula dilation was the primary use of a 4 mm balloon catheter with a stainless steel stylet. The stent deployment was modified by deploying the metal stent inside a bile duct (half of the stent) under EUS and fluoroscopic guidance and gently pulling the echoendoscope after full deployment of the stent inside the echoendoscope channel (remaining portion of the stent) under fluoroscopic guidance. This cohort was compared with a matched historical cohort. In phase I, the technical and clinical success with the modified method was 96% (27/28) and 89% (24/27 as per-protocol analysis). The overall adverse event rate was 7%. In phase II, there was no difference in technical and clinical success, stent patency and overall adverse events in each group. However, the procedural time (15.3 ± 5.2 min vs 22.3 ± 6.0 min, P < 0.001) and early adverse events (0% vs 26%, P = 0.02) were statistically improved in case cohort compared with control cohort. Compared with the conventional EUS-HGS technique, the procedural time was shorter and early adverse events were less frequent with our simplified and modified technique.
    World Journal of Gastroenterology 05/2014; 20(17):5051-9. · 2.55 Impact Factor
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    ABSTRACT: Kikuchi-Fujimoto disease (KFD) is a benign disease, which is characterized by a cervical lymphadenopathy with fever, and it often mimics malignant lymphoma (ML). 2-[(18)F]fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) is a powerful imaging modality for the diagnosis, staging and monitoring of ML, with the limitations including the nonspecific FDG uptake in infectious or inflammatory processes. This study compared clinical manifestations and PET/CT findings between KFD and ML patients.
    Korean Journal of Pediatrics 05/2014; 57(5):226-31.
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    Jae Beom Hong, Kil-Ho Cho, Joon Hyuk Choi
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    ABSTRACT: Periosteal osteosarcoma is an extremely rare chondroblastic osteosarcoma in the flat bone. There were authors reporting of two cases of periosteal osteosarcoma in the highly unusual sites. One of them arose from the rib, in a 17-year-old male, which appeared as a hypodense juxtacortical mass with periosteal reaction on CT. The other one arose from the scapula, in a 17-year-old female, which showed the intermediate signal intensity (SI) on T1-weighted image (WI), heterogeneous high SI on T2WI, and rim-enhancement on contrast-enhanced T1WI with cortical destruction on MRI.
    Korean journal of radiology: official journal of the Korean Radiological Society 05/2014; 15(3):370-5. · 1.32 Impact Factor
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    ABSTRACT: Background/Aims: A retrospective analysis was performed to evaluate the safety and effectiveness of extracorporeal shock wave lithotripsy (ESWL) for pancreatolithiasis on successive days under intravenous bolus of pethidine alone. Methods: Ninety patients with calcified pancreatic stones (≥5 mm) presenting with abdominal pain were selected for ESWL. ESWL was performed with an electroconductive lithotripter under fluoroscopic target systems. Fragmented calculi after ESWL were removed by endotherapy. Results: A mean of 4.2 ESWL sessions were performed for each patient, with a mean of 2,984 shocks at a mean power setting of 12.8 kV. Eighty-four (89.3%) patients underwent ESWL for three or more days in a row. Fragmentation of the stones were achieved in 83/90 (92.2%) patients. Complete clearance of the main pancreatic duct was achieved in 54/90 (60.0%) patients, and partial clearance was achieved in 27 (30.0%) patients. The mean dose of pethidine used during ESWL was 53.5±20.7 mg per session. As ESWL-related complications, four (4.3%) patients developed mild acute pancreatitis. Conclusions: In case of endoscopically difficult-to-treat pancreatic duct stones, combined therapy with ESWL is an effective method, and treatment with multiple sessions of ESWL on successive days under intravenous bolus of pethidine alone is safe and well tolerated. (Korean J Gastroenterol 2014;63:231-238).
    The Korean journal of gastroenterology = Taehan Sohwagi Hakhoe chi 04/2014; 63(4):231-8.
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    ABSTRACT: Background/Aims: Biliary drainage is performed in many patients with cholangiocarcinoma (CCA) to relieve obstructive jaundice. For those who have undergone biliary drainage, bile cytology can be easily performed since the access is already achieved. This study aims to determine the clinical usefulness of bile cytology for the diagnosis of CCA and to evaluate factors affecting its diagnostic yield. Methods: A total of 766 consecutive patients with CCA underwent bile cytology via endoscopic nasobiliary drainage or percuta-neous transhepatic biliary drainage from January 2000 to June 2012. Data were collected by retrospectively reviewing the medical records. We evaluated the diagnostic yield of bile cytology with/without other sampling methods including brush cytology and endobiliary forcep biopsy, and the optimal number of repeated bile sampling. Several factors affecting diagnostic yield were then analyzed. Results: The sensitivity of bile cytology, endobiliary forceps biopsy, and a combination of both sampling methods were 24.7% (189/766), 74.4% (259/348), and 77.9% (271/348), respectively. The cumulative positive rate of bile sampling increased from 40.7% (77/189) at first sampling to 93.1% (176/189) at third sampling. On multivariate analysis, factors associated with positive bile cytology were perihilar tumor location, intraductal growing tumor type, tumor extent ≥20 mm, poorly differ-entiated grade tumor, and three or more samplings. Conclusions: Although bile cytology itself has a low sensitivity in diagnosing CCA, it has an additive role when combined with endobiliary forceps biopsy. Due to the relative ease and low cost, bile cytology can be considered a reasonable complementary diagnostic tool for diagnosing CCA. (Korean J Gastroenterol 2014;63:107-113).
    The Korean journal of gastroenterology = Taehan Sohwagi Hakhoe chi 02/2014; 63(2):107-13.
  • Mi Jin Gu, Joon Hyuk Choi
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    ABSTRACT: The aim of this study was to evaluate the epithelial-mesenchymal transition (EMT) and to assess its prognostic significance in intrahepatic cholangiocarcinoma. We performed immunohistochemical stainings for E-cadherin, β-catenin, vimentin and fibronectin in a total of 85 cases. Expression of vimentin and reduced expression of E-cadherin were found to show correlation with poor differentiation (p=0.017, p=0.010). Reduced expression of β-catenin showed significant association with poor differentiation (p=0.023), tumour size (p=0.028) and lymph node metastasis (p=0.011). According to the expression pattern of E-cadherin, β-catenin, vimentin and fibronectin we categorised four phenotypes: complete type, hybrid type, null type and wild type. The complete type of β-catenin with vimentin or fibronectin was found to show an association with lymph node metastasis (p=0.048, p=0.012). Significantly worse overall survival (OS) and disease-free survival (DFS) was observed for the complete type, and the best OS and DFS were observed for the wild type. EMT phenotypes can be useful markers for prediction of patient outcomes.
    Journal of clinical pathology 09/2013; · 2.43 Impact Factor
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    Joon Hyuk Choi, Sung Koo Lee
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    ABSTRACT: Percutaneous transhepatic cholangioscopy (PTCS) is the most widely used modality for diagnosis and treatment of biliary disease. Although many other novel technologies have been developed based on recent advances in endoscopy, PTCS has its own role. In diagnostics, PTCS is used for evaluation of indeterminate biliary strictures, bile duct tumors, and postoperative biliary strictures that cannot be reached by a peroral approach. In therapeutics, the removal of bile duct stones, dilatation of bile duct strictures including postoperative anastomosis site strictures, and local tumor therapy are indications of PTCS. Especially in a therapeutic role, PTCS has the advantage of maneuverability due to a shorter endoscopic length compared to other cholangioscopic modalities. Hence, PTCS has its own indispensable diagnostic and therapeutic roles.
    Clinical endoscopy. 09/2013; 46(5):529-536.
  • Mi-Jin Gu, Young-Kyung Bae, Joon Hyuk Choi
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    ABSTRACT: Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors in the gastrointestinal tract and are mostly driven by KIT and PDGFRA-activation mutations. However, other signaling pathways are involved in pathogenesis and proliferation of GISTs. This study investigates the prognostic significance of insulin-like growth factor 1 (IGF1) and IGF1 receptor (IGF1R) and the role of succinate dehydrogenase subunit B (SDHB) in GISTs. Immunohistochemistry (IHC) for IGF1, IGF1R and SDHB was performed in total of 165 GISTs. The overexpression of IGF1 was evident in tumors with high mitotic count, large tumor size and was correlated with high risk of malignant behavior. IGF1R overexpression was correlated with IGF overexpression, high mitotic count and high risk of malignant behavior. Loss of expression for SDHB was found in only 2 gastric GISTs. The overexpression of IGF1 and IGF1R can be useful marker to predict relapse and aggressive behavior in GISTs and has prognostic implications.
    Hepato-gastroenterology 09/2013; 60(126):1383-6. · 0.77 Impact Factor
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    ABSTRACT: Hydatid cysts (echinococcosis) are caused by an infestation with larval tapeworms of the genus Echinococcus. The disease is extensively distributed worldwide, and it has been rarely reported in Korea. We describe the cytologic features of a case of hepatic hydatid cyst in a 28-year-old male. Computed tomography revealed a cystic mass in the right lobe of the liver. A right hemihepatectomy was performed. The aspirated fluid from the hepatic cystic mass was clear. The smears showed protoscolices, hooklets, and a laminated membrane.
    The Korean Journal of Pathology 08/2013; 47(4):395-8. · 0.17 Impact Factor
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    ABSTRACT: A 58-year-old woman presented with a solitary myofibroma that arose in the sigmoid colon. Computed tomography revealed a highly enhanced intramural mass (1.3-cm maximum diameter) in the proximal sigmoid colon. Histologically, the tumor exhibited a biphasic growth pattern, which comprised haphazardly arranged, interwoven fascicles of plump, myoid-appearing spindle cells with elongated nuclei and abundant eosinophilic cytoplasm, and more cellular areas of primitive-appearing polygonal cells that were arranged in a hemangiopericytomatous pattern. The tumor cells were positive for smooth muscle actin (SMA), and negative for desmin, h-caldesmon, CD34, cytokeratin, S100 protein, and CD117. The Ki-67 labeling index was not high (up to 7%). Based on these histologic and immunohistochemical features, our patient was diagnosed with a myofibroma of the sigmoid colon. The presence of solitary myofibroma in the intestine of an adult requires attention to avoid misdiagnosis as a more aggressive mesenchymal tumor. Virtual Slides The virtual silde(s) for this article can be found here:
    Diagnostic Pathology 06/2013; 8(1):90. · 1.85 Impact Factor
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    ABSTRACT: Soft tissue myoepithelioma is a rare neoplasm composed of myoepithelial cells. Here, we describe the cytologic features of soft tissue myoepithelioma arising on the right forearm in an 18-year-old man. The excised tumor (3.0×1.8×1.5 cm) was well-demarcated, yellow-gray, soft, and myxoid. The cytologic smears showed round to spindle, epithelioid, and plasmacytoid cells in the myxoid background. The nuclei were uniform, round to ovoid, with finely distributed chromatin and eosinophilic or pale cytoplasm. The tumor cells demonstrated immunoreactivity for cytokeratin (AE1/AE3), epithelial membrane antigen, S100 protein, and glial fibrillary acidic protein. Electron microscopy showed intermediate filaments, desmosomes, and basal lamina.
    The Korean Journal of Pathology 06/2013; 47(3):299-303. · 0.17 Impact Factor
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    ABSTRACT: There is confusion in the diagnosis and biological behaviors of gastroenteropancreatic neuroendocrine tumors (GEP-NETs), because of independently proposed nomenclatures and classifications. A standardized form of pathology report is required for the proper management of patients. We discussed the proper pathological evaluation of GEP-NET at the consensus conference of the subcommittee meeting for the Gastrointestinal Pathology Study Group of the Korean Society of Pathologists. We then verified the prognostic significance of pathological parameters from our previous nationwide collection of pathological data from 28 hospitals in Korea to determine the essential data set for a pathology report. Histological classification, grading (mitosis and/or Ki-67 labeling index), T staging (extent, size), lymph node metastasis, and lymphovascular and perineural invasion were significant prognostic factors and essential for the pathology report of GEP-NET, while immunostaining such as synaptophysin and chromogranin may be optional. Furthermore, the staging system, either that of the 2010 American Joint Cancer Committee (AJCC) or the European Neuroendocrine Tumor Society (ENETS), should be specified, especially for pancreatic neuroendocrine neoplasms. A standardized pathology report is crucial for the proper management and prediction of prognosis of patients with GEP-NET.
    The Korean Journal of Pathology 06/2013; 47(3):227-37. · 0.17 Impact Factor
  • Gastrointestinal endoscopy 05/2013; · 6.71 Impact Factor
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    ABSTRACT: BACKGROUND: The differential diagnosis between benign and malignant polyps of the gallbladder (GB) is often challenging. OBJECTIVES: To evaluate whether contrast-enhanced harmonic EUS (CEH-EUS) might be an accurate method for discriminating malignant GB polyps from benign polyps. DESIGN: Observational study. SETTING: Tertiary care medical center. PATIENTS: Ninety-three patients with GB polyps larger than 10 mm in diameter that were detected by conventional EUS underwent CEH-EUS for evaluation of microvasculature. INTERVENTION: CEH-EUS was performed using a radial echoendoscope and the extended pure harmonic detection mode. MAIN OUTCOME MEASUREMENTS: The abilities of conventional EUS and CEH-EUS to diagnose malignant polyp were compared. Two blinded reviewers classified the perfusion images into 3 categories: diffuse enhancement, perfusion defect, or nonenhancement. The vessel images were categorized as having a regular spotty vessel, an irregular vessel, or no vessels. RESULTS: An irregular vessel pattern determined by CEH-EUS aided in the diagnosis of malignant polyps with a sensitivity and specificity of 90.3% and 96.6%, respectively. The presence of perfusion defects, determined by CEH-EUS, was calculated to diagnose malignant polyps with a sensitivity and specificity of 90.3% and 94.9%, respectively. Based on the definitely determined diagnosis, sensitivity and specificity for CEH-EUS were 93.5% and 93.2% versus 90.0% and 91.1% for conventional EUS. In 8 cases, management changed after CEH-EUS. LIMITATIONS: A tertiary medical center with a limited number of patients. CONCLUSIONS: The presence of irregular intratumoral vessels or perfusion defects seen on CEH-EUS may be sensitive and accurate predictors of malignant GB polyps. CEH-EUS offers slightly improved diagnostic accuracy compared with EUS.
    Gastrointestinal endoscopy 04/2013; · 6.71 Impact Factor
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    ABSTRACT: AIM: The vascular endothelial growth factor (VEGF) or its family might play role in tumor-related angiogenesis in gastrointestinal stromal tumors (GIST), thereby affecting the prognosis. Accordingly, the present study analyzed the impact of VEGF and VEGF receptor-2 (VEGFR-2) gene polymorphisms on the prognosis for GIST patients. METHODS: In all, 213 consecutive patients with GIST from five medical centers were enrolled in the present study. The genomic DNA was extracted from paraffin-embedded tumor tissue, and four VEGF (-2578C/A, -1498C/T, -634G/C, and +936C/T) and one VEGFR-2 (+1416A/T) gene polymorphisms were determined using a Sequenom MassARRAY system. RESULTS: With a median follow up of 18.4 months, the estimated 5-year relapse-free survival and overall survival rates were 70 and 87%, respectively. In a multivariate analysis including age, sex, primary site of disease, pathology and risk stratification, no significant association was observed between the polymorphism of the VEGF and VEGFR-2 genes and survival. CONCLUSION: None of the five VEGF and VEGFR-2 gene polymorphisms investigated in this study was found to be an independent prognostic marker for Korean patients with surgically resected GIST. However, further studies on a larger scale are warranted to clarify the role of VEGF and VEGFR gene polymorphisms as a prognostic biomarker for GIST patients.
    Asia-Pacific Journal of Clinical Oncology 04/2013; · 0.91 Impact Factor
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    ABSTRACT: Recently we demonstrated that SAA induces macrophage foam cell formation. In this study we show that SAA-induced foam cell formation is inhibited by formyl peptide receptor 2 (FPR2) antagonist WRW(4), as well as by FPR2-targeted siRNA knockdown. SAA-stimulated LOX1 expression was also mediated by FPR2. We also found that SAA-stimulated foam cell formation and LOX1 expression was pertussis toxin-insensitive. In addition, FPR2 is upregulated in peripheral blood mononuclear cells from patients with atherosclerosis. Our findings therefore suggest that SAA stimulates foam cell formation via FPR2 signaling and LOX1 induction, and thus likely contributes to atherogenesis.
    Biochemical and Biophysical Research Communications 03/2013; · 2.28 Impact Factor
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    ABSTRACT: Elevated levels of serum amyloid A (SAA) is a risk factor for cardiovascular diseases, however, the role of SAA in the pathophysiology of atherosclerosis remains unclear. Here we show that SAA induced macrophage foam cell formation. SAA-stimulated foam cell formation was mediated by c-jun N-terminal kinase (JNK) signaling. Moreover, both SAA and SAA-conjugated high density lipoprotein stimulated the expression of the important scavenger receptor lectin-like oxidized low-density lipoprotein receptor 1 (LOX1) via nuclear factor-κB (NF-κB). A LOX1 antagonist carrageenan significantly blocked SAA-induced foam cell formation, indicating that SAA promotes foam cell formation via LOX1 expression. Our findings therefore suggest that SAA stimulates foam cell formation via LOX1 induction, and thus likely contributes to atherogenesis.
    Biochemical and Biophysical Research Communications 02/2013; · 2.28 Impact Factor
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    Mi Jin Gu, Joon Hyuk Choi, So Hyun Kim
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    ABSTRACT: Vascular abnormality of the intestine is rare, except angiodysplasia. We report on an unusual case of atypical florid vascular proliferations of the appendix. A 41-year old male presented with melena. Adhesioned blood clots in the appendiceal orifice were observed by colonoscopy. He underwent laparoscopic appendectomy. Microscopically, a tiny exophytic polypoid mass was observed. The mass showed pyogenic granuloma-like features in the superficial portion and infiltrative florid vascular proliferations in the deeper portion. Endothelial cells showed minimal nuclear atypia, and mitotic figures were observed infrequently and showed positivity for CD31 and CD34 and negativity for HHV-8. Differential diagnoses include from benign vascular tumor to angiosarcoma or Kaposi's sarcoma, but this lesion does not fit the description of any defined vascular entity. We diagnosed atypical florid vascular proliferations and the patient has been well during the fivemonth postoperative follow-up. Virtual Slide The virtual slide(s) for this article can be found here:
    Diagnostic Pathology 01/2013; 8(1):12. · 1.85 Impact Factor
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    ABSTRACT: As a result of various independently proposed nomenclatures and classifications, there is confusion in the diagnosis and prediction of biological behavior of gastroenteropancreatic neuroendocrine tumors (GEP-NETs). A comprehensive nationwide study is needed in order to understand the biological characteristics of GEP-NETs in Korea. We collected 4,951 pathology reports from 29 hospitals in Korea between 2000 and 2009. Kaplan-Meier survival analysis was used to determine the prognostic significance of clinicopathological parameters. Although the GEP-NET is a relatively rare tumor in Korea, its incidence has increased during the last decade, with the most significant increase found in the rectum. The 10-year survival rate for well-differentiated endocrine tumor was 92.89%, in contrast to 85.74% in well differentiated neuroendocrine carcinoma and 34.59% in poorly differentiated neuroendocrine carcinoma. Disease related death was most common in the biliary tract (62.2%) and very rare in the rectum (5.2%). In Kaplan-Meier survival analysis, tumor location, histological classification, extent, size, mitosis, Ki-67 labeling index, synaptophysin expression, lymphovascular invasion, perineural invasion, and lymph node metastasis showed prognostic significance (p<0.05), however, chromogranin expression did not (p=0.148). The 2000 and 2010 World Health Organization (WHO) classification proposals were useful for prediction of the prognosis of GEP-NET. The incidence of GEP-NET in Korea has shown a remarkable increase during the last decade, however, the distribution of tumors in the digestive system differs from that of western reports. Assessment of pathological parameters, including immunostaining, is crucial in understanding biological behavior of the tumor as well as predicting prognosis of patients with GEP-NET.
    Cancer Research and Treatment 09/2012; 44(3):157-65. · 1.96 Impact Factor

Publication Stats

188 Citations
73.20 Total Impact Points


  • 2013–2014
    • Asan Medical Center
      • Department of Gastroenterology
      Sŏul, Seoul, South Korea
  • 2002–2014
    • Yeungnam University
      • • Department of Pathology
      • • College of Medicine
      • • Division of Internal Medicine
      • • Department of Neurosurgery
      • • Department of Diagnostic Radiology
      Onyang, South Chungcheong, South Korea
  • 2009–2013
    • Ulsan University Hospital
      Urusan, Ulsan, South Korea
  • 2010
    • Inje University
      • College of Medicine
      Kimhae, South Gyeongsang, South Korea