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Dive into the research topics where Shawn Mallery is active.

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Featured researches published by Shawn Mallery.


Gastrointestinal Endoscopy | 2004

EUS-guided rendezvous drainage of obstructed biliary and pancreatic ducts: Report of 6 cases.

Shawn Mallery; Jake Matlock; Martin L. Freeman

BACKGROUND Only a few cases have been reported of EUS-guided drainage of obstructed pancreatic or bile ducts. An initial experience with EUS-guided rendezvous drainage after unsuccessful ERCP is reported. METHODS EUS-guided transgastric or transduodenal needle puncture and guidewire placement through obstructed pancreatic (n=4) or bile (n=2) ducts was attempted in 6 patients. Efforts were made to advance the guidewire antegrade across the papilla or surgical anastomosis. If guidewire passage was successful, rendezvous ERCP with stent placement was performed immediately afterward. RESULTS EUS-guided duct access and intraductal guidewire placement was accomplished in 5 of 6 cases, with successful traversal of the obstruction, and rendezvous ERCP, with stent placement in 3 of 6 cases (two biliary, one pancreatic). The procedure was clinically effective in all successful cases (two patients with malignant obstructive jaundice, one with relapsing pancreatitis after pancreaticoduodenectomy). There was one minor complication (transient fever) but no pancreatitis or duct leak after successful or unsuccessful procedures. CONCLUSIONS EUS is a feasible technique for allowing rendezvous drainage of obstructed biliary or pancreatic ducts through native papillae or anastomoses after initially unsuccessful ERCP.


Endoscopy | 2010

Endoscopic ultrasound rendezvous for bile duct access using a transduodenal approach: cumulative experience at a single center. A case series

Yeon Suk Kim; K. Gupta; Shawn Mallery; Rebecca Li; Timothy Kinney; M. L. Freeman

Endoscopic ultrasound (EUS)-assisted biliary access is utilized when conventional endoscopic retrograde cholangiopancreatography (ERCP) fails. We report a 10-year experience utilizing a transduodenal EUS rendezvous via a transpapillary route without dilation of the transduodenal tract, followed by immediate ERCP access. Patients included all EUS-guided rendezvous procedures for biliary access that were performed following ERCP failure. EUS-assisted bile duct puncture was performed via a transduodenal approach and a guide wire was advanced through the papilla without any dilation or bougienage of the tract; ERCP was performed immediately afterwards. EUS-assisted biliary rendezvous was attempted in 15 patients (mean age 66 +/- 18.2 years; malignant = 10, benign = 5). Mean diameter of measured bile ducts was 14.3 +/- 5.17 mm (range 4-23 mm). The reasons for initial ERCP failure were tumor infiltration or edema (n = 9), intradiverticular papilla (n = 2), pre-existing duodenal stent (n = 1), and anatomic anomalies (n = 3). Successful EUS-guided bile duct puncture and wire passage were achieved in all 15 patients (100 %), with drainage being successful in 12 / 15 (80 %). Failures occurred in three patients due to inability to traverse the biliary stricture (n = 2) or dissection of a choledochocele with the guide wire (n = 1); all were subsequently drained via percutaneous methods. Stents placed were metallic in eight patients and plastic in four. Complications consisted of moderate pancreatitis after a difficult ERCP attempt in one patient, and bacteremia after percutaneous biliary drainage in another. There were no instances of perforation, extraluminal air or fluid collections. EUS-assisted biliary drainage utilizing a transduodenal rendezvous approach demonstated a high success rate without any complications directly attributable to the EUS access. Advantages over percutaneous biliary and other methods of EUS biliary access include performance under the same anesthesia, and a very small-caliber needle puncture similar to EUS/fine-needle aspiration.


American Journal of Clinical Pathology | 2003

Intraductal Papillary-Mucinous Neoplasm of the Pancreas The Findings and Limitations of Cytologic Samples Obtained by Endoscopic Ultrasound-Guided Fine-Needle Aspiration

Edward B. Stelow; Michael W. Stanley; Ricardo H. Bardales; Shawn Mallery; Rebecca Lai; Bradley M. Linzie; Stefan E. Pambuccian

All clinically and ultrasonographically suspected examples of intraductal papillary-mucinous neoplasm (IPMN) aspirated during a 17-month period were reviewed and analyzed for follow-up. We identified 18 cases of suspected IPMN in patients 52 to 87 years old. All patients had dilated pancreatic ducts, with 3 showing sonographically apparent intraductal papillary lesions; 5 had adjacent cystic or solid pancreatic masses. Cytologic preparations showed thick, glistening, viscid, abnormal mucus in all cases. Aspirates from 13 lesions (72%) were acellular or sparsely cellular, but entrapped single or loosely cohesive neoplastic cells were identified in 16 cases (89%). Goblet cell morphologic features were common (6/18 [33%]), but papillary clusters and dysplastic changes were infrequent (3 [17%] each). In keeping with current therapeutic thinking, confirmatory histologic follow-up was available for only 4 patients (22%), as most people with lesions clinically, sonographically, and cytologically consistent with IPMN are elderly and often have comorbid conditions. Although endoscopic ultrasound-guided fine-needle aspiration has important limitations, gross and cytologic findings can aid in confirming the suspected diagnosis, and integration of complete clinical, sonographic, and cytologic information may be the best way to reach the most accurate diagnosis possible.


American Journal of Clinical Pathology | 2003

Endoscopic Ultrasound–Guided Fine-Needle Aspiration Findings of Gastrointestinal Leiomyomas and Gastrointestinal Stromal Tumors

Edward B. Stelow; Michael W. Stanley; Shawn Mallery; Rebecca Lai; Bradley M. Linzie; Ricardo H. Bardales

True leiomyomas of the gastrointestinal system are rare but remain the most common mesenchymal tumors of the esophagus. It has become important to distinguish these tumors from gastrointestinal stromal tumors (GISTs) because the neoplasms have different prognoses and treatment options. We describe and compare clinical findings and the following fine-needle aspiration (FNA) features of 9 gastrointestinal leiomyomas and 19 GISTs sampled with endoscopic ultrasound: overall cellularity, cell group features, cell shape and cytoplasmic features, nuclear characteristics, background, cell block features, and immunohistochemical results. Gastrointestinal leiomyomas and GISTs have different clinical and cytologic features that help pathologists distinguish these tumors, and the immunohistochemical findings that help define these lesions can be derived readily from cell block material obtained by endoscopic ultrasound-guided FNA.


Clinical Gastroenterology and Hepatology | 2012

Histologic and Imaging Features of Mural Nodules in Mucinous Pancreatic Cysts

Ning Zhong; Lizhi Zhang; Naoki Takahashi; Vladislav Shalmiyev; Marcia I. Canto; Jonathan E. Clain; John C. Deutsch; John M. DeWitt; Mohamad A. Eloubeidi; Ferga C. Gleeson; Michael J. Levy; Shawn Mallery; Massimo Raimondo; Elizabeth Rajan; Tyler Stevens; Mark Topazian

BACKGROUND & AIMS Mural nodules predict malignancy within pancreatic cysts, but it is not clear whether endoscopic ultrasound (EUS) and computed tomography (CT) accurately identify nodules. We assessed images and the histology of mural nodules in branch duct intraductal papillary mucinous neoplasms (BD-IPMNs) and mucinous cystic neoplasms (MCNs) and identified criteria to distinguish mural nodules from mucus. METHODS We reviewed pathology specimens and EUS and CT images from consecutive patients with resected BD-IPMNs or MCNs. A blinded interobserver study of the EUS images was then conducted to identify features that distinguished nodules from mucus. After education about these features, the raters interpreted the EUS images again. RESULTS On the basis of histologic analysis, 22 of 57 cases had epithelial nodules. Cancer or high-grade dysplasia was found in 23% of cysts with nodules versus 3% without nodules (P = .02). On the basis of reports, EUS detected epithelial nodules with 75% sensitivity and 83% specificity, whereas these values were 24% and 100%, respectively, for CT. Mucus accounted for 65% of intracystic lesions detected by EUS and was often diagnosed by using change in body position and fine-needle aspiration. Interobserver analysis identified 3 features that were detected by EUS (echogenicity, edge, and rim) that distinguished mucus from epithelial nodules. The diagnostic accuracy of the raters improved from a mean of 57% to 79% after education about these features (P = .004); accuracy was 90% when all 3 features of mucus were present. CONCLUSIONS Malignancy is associated with epithelial nodules in BD-IPMNs and MCNs, but most echogenic lesions detected in cysts by EUS are mucus. Knowledge of features that discriminate mucus from mural nodules improves the diagnostic accuracy of EUS.


Endoscopy | 2009

Therapeutic pancreatic endoscopy after Whipple resection requires rendezvous access

Timothy Kinney; Rebecca Li; K. Gupta; Shawn Mallery; David Hunter; Eric H. Jensen; Selwyn M. Vickers; Martin L. Freeman

Chronic pancreatic complications after pancreaticoduodenectomy, including strictured pancreaticojejunostomy and pancreatic fistulas, may be amenable to endoscopic therapy. To date there is no published series focusing on pancreatic endotherapy in this group of patients. We report our experience performing pancreatic therapeutic endoscopic retrograde cholangiopancreatography (ERCP) in 10 patients after pancreaticoduodenectomy. All patients had evidence of pancreatic anastomotic obstruction by endoscopic ultrasound (EUS) or secretin-enhanced magnetic resonance cholangiopancreatography. Technical endoscopic success and clinical outcomes were measured. Technically successful endoscopic access and therapy was ultimately achieved by ERCP in eight of the 10 patients. Although a duodenoscope or pediatric colonoscope could be advanced up the afferent limb in all patients, initial unassisted pancreatic cannulation and therapy was successful in only one patient. Rendezvous techniques, either percutaneous or EUS-guided, were required for endoscopic access in the other 9 patients. Complications included moderate pancreatitis with retroperitoneal air after percutaneous rendezvous access in 1 patient, and fever in 1 patient. Therapeutic pancreatic ERCP for chronic complications after Whipple pancreaticoduodenectomy is feasible but quite challenging. Endoscopic access through a stenotic pancreaticojejunal anastomosi generally requires either EUS or percutaneous rendezvous assistance.


Cancer | 2006

Fine‐needle aspiration cytology of pancreatic lymphoepithelial cysts

Maria Luisa C. Policarpio-Nicolas; Vanessa M. Shami; Michel Kahaleh; Reid B. Adams; Shawn Mallery; Michael W. Stanley; Ricardo H. Bardales; Edward B. Stelow

Lymphoepithelial cysts (LECs) of the pancreas are extremely rare, benign, nonneoplastic cysts that can mimic pseudocysts or cystic neoplasms clinically and radiographically. The cytologic features of LECs have been described only in a handful of case reports and may overlap with both benign and malignant pancreatic tumors.


Clinical Update | 2003

The role of endoscopy in the evaluation and management of patients with suspected pancreatic malignancy

Todd H. Baron; Shawn Mallery; Grace Elta

Abstract Commentary Pancreatic cancer is the second most frequent gastrointestinal malignancy with approximately 29,000 new cases occurring annually in the United States. Almost all of these patients will die from the disease, making pancreatic cancer the fourth leading cause of cancer death for both men and women. Since surgical resection of the tumor offers the only chance for a cure, modalities for early diagnosis and accurate preoperative staging have continued to evolve. In this review, Drs. Mallery and Baron discuss the role of new diagnostic modalities including helical or multi-detector CT scan, endoscopic ultrasound (EUS), EUS-guided fine needle aspirate, and MRI, MRCP, and MR angiography. ERCP is now primarily relegated to a therapeutic palliative role in inoperable patients. A clinical management algorithm for patients with suspected pancreatic cancer is provided.


American Journal of Clinical Pathology | 2008

A limited immunocytochemical panel for the distinction of subepithelial gastrointestinal mesenchymal neoplasms sampled by endoscopic ultrasound-guided fine-needle aspiration.

Edward B. Stelow; Faris Murad; Steven M. Debol; Michael W. Stanley; Ricardo H. Bardales; Rebecca Lai; Shawn Mallery

We studied the use of immunocytochemical analysis with material procured by endoscopic ultrasound-guided fine-needle aspiration (EUS-guided FNA) for the diagnosis of subepithelial intramural gastrointestinal (GI) mesenchymal neoplasms (SIGIMNs). We identified all EUS-guided FNA specimens of SIGIMNs that had undergone immunocytochemical analysis. Results were compared with follow-up histologic diagnoses. There were 95 aspirates that were diagnosed as GI mesenchymal tumors (GI stromal tumors [GISTs], n = 46), leiomyomas (n = 38), peripheral nerve sheath tumors (n = 5), and other neoplasms by cytologic examination. Immunoreactivity with antibodies to CD117 always predicted GIST at follow-up; 15 of 16 cases immunoreactive with antibodies to CD34 were found to be GISTs at follow-up. Strong immunoreactivity with antibodies to smooth muscle actin or desmin usually predicted a leiomyoma at follow-up aside from a single glomus tumor and a case with apparent nonneoplastic smooth muscle contaminant. When sufficient material is present, immunocytochemical analysis used with material obtained by EUS-guided FNA is highly predictive of final pathologic diagnosis.


The American Journal of Gastroenterology | 2014

Endoscopic interventions for necrotizing pancreatitis.

Guru Trikudanathan; Rajeev Attam; Mustafa A. Arain; Shawn Mallery; Martin L. Freeman

Interventions for necrotizing pancreatitis have undergone a paradigm shift away from open surgical necrosectomy and toward minimally invasive techniques, with endoscopic transmural drainage (ETD) and necrosectomy emerging as principle forms of treatment. Recent multicenter studies, randomized trials, evidence-based guidelines, and consensus statements have endorsed the safety and efficacy of endoscopic and other minimally invasive techniques for the treatment of walled-off necrosis. A comprehensive review of indications, standard and novel approaches, outcomes, complications, and controversies regarding ETD and necrosectomy is presented. Given the inherent challenges and associated risks, endoscopic techniques for the management of necrotizing pancreatitis should be performed at specialized multidisciplinary centers by expert endoscopists well versed in the management of necrotizing pancreatitis.

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Rebecca Lai

Hennepin County Medical Center

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Rajeev Attam

University of Minnesota

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Ricardo H. Bardales

Hennepin County Medical Center

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Kapil Gupta

Cedars-Sinai Medical Center

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Michael W. Stanley

Hennepin County Medical Center

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Steven M. Debol

Hennepin County Medical Center

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