Hyun Sung Kim

Complications of congenital and developmental abnormalities of the gastrointestinal tract in adolescents and adults: evaluation with multimodality imaging.

There is a wide variety of congenital anomalies that may affect the gastrointestinal tract. Most symptomatic congenital anomalies are found in newborns and infants. Such anomalies are relatively rare in adolescents and adults, and they may be difficult to identify because clinical symptoms often are nonspecific and insidious, causing them to be mistaken for other common abdominal conditions. Multimodality imaging is useful in evaluating congenital anomalies of the gastrointestinal tract in adults. The imaging features at radiography, fluoroscopy, ultrasonography, computed tomography, and magnetic resonance imaging may help identify congenital gastrointestinal anomalies such as congenital esophageal stenosis, gastric volvulus, duodenal web, annular pancreas, heterotopic pancreas, cecal volvulus, anomalies of the omphalomesenteric duct, Hirschsprung disease, and gastrointestinal duplication cyst. Familiarity with the imaging features of the various congenital anomalies of the gastrointestinal tract and their complications is important to establish the correct diagnosis and determine appropriate treatment, which is critical to avoid life-threatening complications.

Diffusion-weighted magnetic resonance imaging for non-neoplastic conditions in the hepatobiliary and pancreatic regions: pearls and potential pitfalls in imaging interpretation

Potentially, diffusion-weighted magnetic resonance imaging (DWI) can assess the functional information on concerning the status of tissue cellularity, because increased cellularity is associated with impeded diffusion. DWI in the hepatobiliary and pancreatic regions has demonstrated the usefulness to detect malignant lesions and differentiate them from benign lesions. However, it has been shown more recently that there is some overlap in ADC values for benign and malignant neoplasms. Moreover, some non-neoplastic lesions in the hepatobiliary and pancreatic regions exhibit restricted diffusion on DWI, because of pus, inflammation, or high cellularity. Focal eosinophilic liver disease, hepatic inflammatory myofibroblastic tumor, granulomatous liver disease, acute cholecystitis, xanthogranulomatous cholecystitis, focal pancreatitis, or autoimmune pancreatitis frequently exhibit restricted diffusion on DWI, which may be confused with malignancy in the hepatobiliary and pancreatic regions. Thus, DWI should not be interpreted in isolation, but in conjunction with other conventional images, to avoid the diagnostic pitfalls of DWI. Nevertheless, the presence of diffusion restriction in the non-neoplastic lesions sometimes provides additional information regarding the diagnosis, in problematic patients where conventional images have yielded equivocal findings. DWI may help differentiate hepatic abscess from malignant necrotic tumors, gallbladder empyema from dense bile or sludge in the gallbladder, and pylephlebitis from bland thrombosis in the portal vein. Therefore, knowledge of DWI findings to conventional imaging findings of diffusion-restricted non-neoplastic conditions in the hepatobiliary and pancreatic regions helps establishing a correct diagnosis.

Spectrum of mucin-producing neoplastic conditions of the abdomen and pelvis: Cross-sectional imaging evaluation

Various mucin-producing neoplasms originate in different abdominal and pelvic organs. Mucinous neoplasms differ from non-mucinous neoplasms because of the differences in clinical outcome and imaging appearance. Mucinous carcinoma, in which at least 50% of the tumor is composed of large pools of extracellular mucin and columns of malignant cells, is associated with a worse prognosis. Signet ring cell carcinoma is characterized by large intracytoplasmic mucin vacuoles that expand in the malignant cells with the nucleus displaced to the periphery. Its prognosis is also generally poor. In contrast, intraductal papillary mucinous neoplasm of the bile duct and pancreas, which is characterized by proliferation of ductal epithelium and variable mucin production, has a better prognosis than other malignancies in the pancreaticobiliary tree. Imaging modalities play a critical role in differentiating mucinous from non-mucinous neoplasms. Due to high water content, mucin has a similar appearance to water on ultrasound (US), computed tomography (CT), and magnetic resonance imaging, except when thick and proteinaceous, and then it tends to be hypoechoic with fine internal echoes or have complex echogenicity on US, hyperdense on CT, and hyperintense on T1- and hypointense on T2-weighted images, compared to water. Therefore, knowledge of characteristic mucin imaging features is helpful to diagnose various mucin-producing neoplastic conditions and to facilitate appropriate treatment.

Patient-Performed Seton Irrigation for the Treatment of Deep Horseshoe Fistula

PURPOSE: Compared with total fistulotomy using a lay-open technique for treatment of deep horseshoe or deep posterior complex anal fistula, the seton drainage method has reduced damage of the external anal sphincter. However, conventional seton drainage is burdensome to patients, requiring frequent clinic visits for wound management during prolonged periods while the drainage tube is in place. To reduce the number of clinic visits and facilitate healing, we devised a patient-performed seton irrigation technique and compared the results with a conventional loose seton to determine its clinical usefulness. METHODS: We reviewed medical records of 24 patients who were diagnosed with deep horseshoe fistula and underwent surgery between January 1999 and December 2004. Twelve patients treated through December 2001 received a conventional loose seton. Twelve patients treated from January 2002 performed self-irrigation via the seton. These 2 groups were compared regarding duration of purulent discharge, length of time until seton removal, and recurrence rate. RESULTS: The mean duration of purulent discharge was 18.75 (range, 15–24) days for self-irrigation vs 29.75 (24–37) days for conventional loose seton treatment (P < .001). The mean time to removal of the seton was 21.58 (18–29) days for self-irrigation vs 32.58 (28–39) days for conventional treatment (P < .001). The recurrence rate after surgery was 8.3% for self-irrigation vs 16.7% for conventional treatment (P > .99). CONCLUSION: Patient-performed seton irrigation shortens the period of treatment and healing through more effective wound management, and we propose this technique as a useful new method of treating deep horseshoe fistula.

NTRK1 fusions for the therapeutic intervention of Korean patients with colon cancer

The identification and clinical validation of cancer driver genes are essential to accelerate the translational transition of cancer genomics, as well as to find clinically confident targets for the therapeutic intervention of cancers. Here we identified recurrent LMNA-NTRK1 and TPM3-NTRK1 fusions in Korean patients with colon cancer (3 out of 147, 2%) through next-generation RNA sequencing (RNA-seq). NTRK1 fusions were mutually exclusive oncogenic drivers of colon cancer that were accompanied with in vitro potential of colony formation and in vivo tumorigenicity comparable to KM12, a human colon cancer cell line harboring TPM3-NTRK1 fusion. NTRK1-encoded TrkA protein was prevalent in 11 out of 216 Korean (5.1%) and 28 out of 472 Chinese patients (5.9%) from independent cohorts, respectively. The expression level of TrkA was significantly correlated with NTRK1 fusion (p = 0.0192), which was verified by a fluorescence in situ hybridization (FISH). Korean patients with TrkA-positive colon cancer had a marginal but significant shorter overall survival time than TrkA-negative colon cancer [hazard ratio (HR) = 0.5346, 95% confidential interval (CI) = 0.2548-0.9722, p = 0.0411]. In addition, KM12 cell line was sensitive to selective TrkA inhibitors. These results demonstrate that NTRK1 fusion is granted as a clinically relevant target for therapeutic intervention of colon cancer.

Transcriptome analysis of paired primary colorectal carcinoma and liver metastases reveals fusion transcripts and similar gene expression profiles in primary carcinoma and liver metastases

BackgroundDespite the clinical significance of liver metastases, the difference between molecular and cellular changes in primary colorectal cancers (CRC) and matched liver metastases is poorly understood.MethodsIn order to compare gene expression patterns and identify fusion genes in these two types of tumors, we performed high-throughput transcriptome sequencing of five sets of quadruple-matched tissues (primary CRC, liver metastases, normal colon, and liver).ResultsThe gene expression patterns in normal colon and liver were successfully distinguished from those in CRCs; however, RNA sequencing revealed that the gene expression between primary CRCs and their matched liver metastases is highly similar. We identified 1895 genes that were differentially expressed in the primary carcinoma and liver metastases, than that in the normal colon tissues. A major proportion of the transcripts, identified by gene expression profiling as significantly enriched in the primary carcinoma and metastases, belonged to gene ontology categories involved in the cell cycle, mitosis, and cell division. Furthermore, we identified gene fusion events in primary carcinoma and metastases, and the fusion transcripts were experimentally confirmed. Among these, a chimeric transcript resulting from the fusion of RNF43 and SUPT4H1 was found to occur frequently in primary colorectal carcinoma. In addition, knockdown of the expression of this RNF43-SUPT4H1 chimeric transcript was found to have a growth-inhibitory effect in colorectal cancer cells.ConclusionsThe present study reports a high concordance of gene expression in the primary carcinoma and liver metastases, and reveals potential new targets, such as fusion genes, against primary and metastatic colorectal carcinoma.

Septic liver: clinical relevance of early inhomogeneous enhancement of the liver in patients with acute pyelonephritis:

Background CT scans of patients with febrile illness occasionally show hepatobiliary changes, although infection does not originate in the hepatobiliary system. These findings may cause radiologists and clinicians to misrecognize hepatobiliary diseases and initiate an inappropriate treatment. Thus, it is important to recognize hepatobiliary CT findings in cases of extrahepatobiliary infectious disease. Purpose To evaluate extrarenal CT manifestations in patients with acute pyelonephritis and to determine the correlation between these extrarenal CT findings and septic liver based on laboratory parameters of sepsis. Material and Methods This study included 157 retrospectively identified patients with confirmed acute pyelonephritis based on CT imaging and urine test, and who had also undergone multi-phase dynamic contrast-enhanced CT scan. Two radiologists reviewed CT findings including early inhomogeneous enhancement of the liver, periportal low density and gallbladder edema, which were correlated with laboratory data including liver function enzymes, albumin, C-reactive protein, white blood cell count, and results of a blood culture by using the Fishers exact test and Mann-Whitney U test. Results Forty-six patients (29.3%) showed early inhomogeneous enhancement of the liver, which was associated with increased C-reactive protein (P < 0.001), a positive blood culture (P < 0.005), and decreased albumin level (P < 0.002). The periportal low density and gallbladder wall edema were noted in 15 patients (9.6%) and six patients (3.8%), respectively. These two CT findings were significantly associated with only decreased albumin level (P < 0.001 and P < 0.040). Conclusion Early inhomogeneous enhancement of the liver in patients with acute pyelonephritis was significantly associated with increased CRP level, a positive blood culture and decreased albumin level, reflecting sepsis and sepsis-associated liver dysfunction, requiring rapid and appropriate intensive treatment.

Curative resection of combined neuroendocrine carcinoma and adenocarcinoma of the gallbladder

Neuroendocrine carcinoma of the gallbladder has very rarely been reported as it accounts for only 0.5% of all neuroendocrine tumors. It has a very aggressive biological behavior. These tumors are usually diagnosed at an advanced stage and surgical management is therefore not an option. We performed a hepatopancreaticoduodenectomy along with adjuvant chemotherapy in a 48-year-old patient with a neuroendocrine carcinoma of the gallbladder. The patient has been followed up at the outpatient clinic for 18 months without there having been any recurrence. Patients with a locally invasive neuroendocrine carcinoma in the gallbladder may benefit from aggressive surgical treatment followed by adjuvant chemotherapy. The primary management in high-grade metastatic tumors is, however, mainly medical.

Distribution and Impact of the Visceral Fat Area in Patients With Colorectal Cancer.

Purpose The purposes of this study were to investigate the distribution of the visceral fat area (VFA) and general obesity and to compare visceral and general obesity as predictors of surgical outcomes of a colorectal cancer resection. Methods The prospectively collected data of 102 patients with preoperatively-diagnosed sigmoid colon or rectal cancer who had undergone a curative resection at Pusan National University Yangsan Hospital between April 2011 and September 2012 were reviewed retrospectively. Men with a VFA of >130 cm2 and women with a VFA of >90 cm2 were classified as obese (VFA-O, n = 22), and the remaining patients were classified as nonobese (VFA-NO, n = 80). Results No differences in morbidity, mortality, postoperative bowel recovery, and readmission rate after surgery were observed between the 2 groups. However, a significantly higher number of harvested lymph nodes was observed in the VFA-NO group compared with the VFA-O group (19.0 ± 1.0 vs. 13.5 ± 1.2, respectively, P = 0.001). Conclusion Visceral obesity has no influence on intraoperative difficulties, postoperative complications, and postoperative recovery in patients with sigmoid colon or rectal cancer.

Diffusion-weighted magnetic resonance imaging of gallbladder adenocarcinoma: analysis with emphasis on histologic grade

PURPOSE To investigate the value of diffusion-weighted imaging (DWI) for differentiating gallbladder adenocarcinoma from adenoma, and predicting histologic grades of gallbladder adenocarcinoma. MATERIALS AND METHODS Fourty-three gallbladder adenocarcinomas and 8 adenomas were included. We compared apparent diffusion coefficient (ADC) values between adenocarcinoma and adenoma, and ADC values of gallbladder adenocarcinoma among the histologic grade. RESULTS Gallbladder adenocarcinoma (1.041×10(-3)mm(2)/s) showed significantly lower ADC values than adenoma (2.039×10(-3)mm(2)/s) (P<.001). Well-differentiated adenocarcinoma (1.290×10(-3)mm(2)/s) showed significantly higher ADC values than higher-grades (1.104×10(-3) and 0.915×10(-3)mm(2)/s in moderately- and poorly-differentiated, respectively) (P<.001). CONCLUSION DWI can help to differentiate gallbladder adenocarcinoma from adenoma, and well-differentiated from higher-grade adenocarcinoma.