Catching the Zebra: Clinical Pearls and Pitfalls for the Successful Diagnosis of Zollinger-Ellison Syndrome

Gastrinoma With Relatively Low Gastrin Levels: A Case Report

Gastrinomas can often be cured with surgical removal if detected early enough. We present a case report where a patient was diagnosed with gastrinoma with relatively low serum gastrin levels after subsequent duodenojejunostomy, gastrojejunostomy, total gastrectomy, and cholecystectomy. With this case report, we hope to promote a higher level of awareness of pancreatic neuroendocrine (NE) tumors and educate clinicians on the full effects of proton pump inhibitor (PPI) use on patient workup, diagnostics, and care.

Ga-68 DOTATATE PET/CT in a patient with Zollinger-Ellison syndrome

This case report follows a 70-year-old male patient with Zollinger-Ellison syndrome undergoing computed tomography (CT) for weight loss and surveillance of bilateral adrenal nodules. Incidentally, diffuse gastric and duodenal wall thickening was noted on CT. The patient underwent esophagogastroduodenoscopy with biopsy results showing well-differentiated neuroendocrine tumors (NET) in the stomach and duodenum. Subsequent imaging with gallium-68 DOTATATE PET/CT showed intense tracer uptake in the stomach and proximal duodenum with liver and regional nodal metastases around the superior mesenteric artery. This case outlines the utility of Ga-68 DOTATATE PET/CT in diagnosing, localizing, and staging NET such as gastrinomas.

Validity of Secretin Stimulation Testing on Proton Pump Inhibitor Therapy for Diagnosis of Zollinger-Ellison Syndrome

INTRODUCTION

Zollinger-Ellison syndrome (ZES) is characterized by gastrinoma-induced hypergastrinemia causing excessive gastric acid secretion. Secretin stimulation tests (SSTs) are required for diagnosis in the majority of patients. Two case reports suggest that proton pump inhibitors (PPIs) cause false SST results. Consequently, PPIs are discontinued to allow hyperchlorhydria to recur; however, uncontrolled acidity can cause life-threatening complications in those with underlying undiagnosed ZES. The aim of this study was to determine whether PPIs influence the validity of SSTs for the diagnosis of ZES.

METHODS

A retrospective chart review was performed. Charts of patients who underwent SSTs were reviewed to determine whether they were performed on or off PPI and the test's accuracy by comparing the results with gold standard tests (diagnostic laboratory testing performed off PPI or surgical pathology consistent with gastrinoma). Sensitivity, specificity, and positive predictive value (PPV) of SST on PPI were calculated and results compared with SST off PPI using noninferiority analyses.

RESULTS

Twenty-eight patients corresponding to 29 SSTs were performed on PPI, and 70 patients corresponding to 107 SSTs were performed off PPI. Most of them were female and white and had multiple endocrine neoplasia type 1. We found no false-positive or false-negative SSTs on PPI. Sensitivity, specificity, and PPV of SSTs on PPI were determined to be noninferior to SSTs off PPI (P ≤ 0.05 for all).

DISCUSSION

In our cohort, SSTs on PPI compared with SSTs off PPI were noninferior for sensitivity, specificity, and PPV. These results suggest that PPI withdrawal before SSTs may not be necessary.

Gastrinoma and Zollinger Ellison syndrome: A roadmap for the management between new and old therapies

Zollinger-Ellison syndrome (ZES) associated with pancreatic or duodenal gastrinoma is characterized by gastric acid hypersecretion, which typically leads to gastroesophageal reflux disease, recurrent peptic ulcers, and chronic diarrhea. As symptoms of ZES are nonspecific and overlap with other gastrointestinal disorders, the diagnosis is often delayed with an average time between the onset of symptoms and final diagnosis longer than 5 years. The critical step for the diagnosis of ZES is represented by the initial clinical suspicion. Hypergastrinemia is the hallmark of ZES; however, hypergastrinemia might recognize several causes, which should be ruled out in order to make a final diagnosis. Gastrin levels > 1000 pg/mL and a gastric pH below 2 are considered to be diagnostic for gastrinoma; some specific tests, including esophageal pH-recording and secretin test, might be useful in selected cases, although they are not widely available. Endoscopic ultrasound is very useful for the diagnosis and the local staging of the primary tumor in patients with ZES, particularly in the setting of multiple endocrine neoplasia type 1. Some controversies about the management of these tumors also exist. For the localized stage, the combination of proton pump inhibitory therapy, which usually resolves symptoms, and surgery, whenever feasible, with curative intent represents the hallmark of gastrinoma treatment. The high expression of somatostatin receptors in gastrinomas makes them highly responsive to somatostatin analogs, supporting their use as anti-proliferative agents in patients not amenable to surgical cure. Other medical options for advanced disease are super-imposable to other neuroendocrine neoplasms, and studies specifically focused on gastrinomas only are scant and often limited to case reports or small retrospective series. The multidisciplinary approach remains the cornerstone for the proper management of this composite disease. Herein, we reviewed available literature about gastrinoma-associated ZES with a specific focus on differential diagnosis, providing potential diagnostic and therapeutic algorithms.

Postsurgical Presentation of Zollinger-Ellison Syndrome After Resection of Endometrioid Neuroendocrine Tumor

Zollinger–Ellison syndrome is a functional neuroendocrine tumor with inappropriate gastrin secretion and hyperchlorhydria causing severe peptic ulcer disease and chronic diarrhea. Although 70% of primary gastrinomas occur in the region of the duodenum, the diagnosis and localization of gastrinomas can be challenging because of small lesions that may arise functionally as lymph node metastases at initial presentation. We report a 76-year-old woman presenting with Zollinger–Ellison syndrome several months after surgical resection of endometrioid small cell neuroendocrine carcinoma and endometrioid adenocarcinoma.

Somatostatin receptor molecular imaging in a misdiagnosed gastrinoma case

Gastrin-secreting tumors, hypergastrinemia and severe ulcer disease form the trademarks of Zollinger-Ellison syndrome (ZES). We report a case of gastrinoma, in a patient who was misdiagnosed for almost five years. The case emphsizes the the special role of functional imaging in the personalized approach to the patient with suggestive symptomatology for NETs. Taking into account that in 80 to 100% of cases of gastroenteropancreatic (GEP) NETs are expressing somatostatin receptors, the functional imaging with radiolabeled somatostatin analogues can be used in order to improve its diagnosis, respectively the treatment of GEP NETs. In the approach to the patient with tremendous digestive symptomatology, physicians from different specialties should evaluate NETs specific markers and then insist on structural-functional complementarity, avoiding the waste of time and high cost of repeated structural investigations. The conclusion of our study is that functional imaging is mandatory in the diagnostic algorithm of gastrinoma.

Gastrinoma in multiple endocrine neoplasia type 1 after total pancreatectomy: A case report

RATIONALE

Surgery for patients with multiple endocrine neoplasia type 1(MEN-1) related gastrinoma remains controversial and total pancreatectomy (TP) has rarely been performed. We reported a case of patient with MEN-1 related gastrinoma treated by TP.

PATIENT CONCERNS

A 46-year-old female was admitted to our hospital due to abdominal distension and diarrhea for 2 years. The patient underwent pituitary tumor resection and kidney stone lithotripsy 10 years ago.

DIAGNOSES

Abdominal computed tomography showed single lesion in the duodenum and multiple lesions throughout the pancreas. The patient's gastrin level was significantly increased (1080 pg/ml). These findings in combination with the pituitary tumor history suggested the presence of gastrinoma associated with MEN-1 syndrome.

INTERVENTION

An exploratory laparotomy was performed. Intraoperative ultrasound confirmed the numerous tumors diffusely distributed throughout the pancreas and the patient eventually underwent TP.

OUTCOMES

Twelve months later, the patient was hospitalized again for anastomotic fistula and underwent a partial gastrectomy, small bowel resection and drainage of the abscess. One month later, she received gastrostomy and jejunostomy due to digestive tract fistula, and died a month later (14 months after TP).

LESSONS

There still might be the possibility of recurrence even after radical surgical resection of gastrinomas, and we suggest the need to measure the basal acid output and maintain regular anti-acid therapy in the long-term follow-up of patients with MEN-1 related gastrinoma.

Chronic diarrhoea in adults: what not to miss

PURPOSE OF REVIEW

Chronic diarrhoea remains a diagnostic challenge, with numerous causes and few effective symptomatic treatments. This review focuses on new methods for diagnosis of common disorders and alerts readers to rarer causes through a systematic approach to the underlying mechanisms.

RECENT FINDINGS

New strategies are emerging to stratify the need for endoscopic investigation. Faecal immunochemical testing, combined with standard blood tests, shows promise in excluding colorectal cancers, adenoma and inflammatory bowel disease, challenging the current use of faecal calprotectin. Serum analysis for markers of bile acid synthesis has been refined, potentially streamlining diagnostic pathways of bile acid malabsorption for those who are unable to access nuclear medicine scans, but the positive predictive value of faecal elastase in low prevalence populations has been questioned. Novel markers such as volatile organic compounds and stool DNA analyses continue to develop.

SUMMARY

A systematic approach to investigation of chronic diarrhoea will ensure all relevant causes are considered and minimize the chance of a missed diagnosis. Combination of clinical features with noninvasive testing supports a judicious approach to endoscopic investigations but further innovation will be needed to resolve the diagnostic challenge that diarrhoea poses.