Schwannoma is a mesenchymal tumor that is mainly located in the peripheral nerves or the central nervous system. Its retroperitoneal location is rare and commonly asymptomatic. Thus, it is usually diagnosed when imaging tests are performed for other purposes. The clinical course of Schwannoma is benign but it also has malignant potential. Therefore, surgical resection is the treatment of choice. The definitive diagnosis is anatomopathological. In this context, we present a patient with retroperitoneal Schwannoma.

We have closely read the article entitled "Pancreatic endocrine tumours or apudomas" (1) published in your journal in April of 2011. Zollinger-Ellison syndrome (ZES) is a rare entity that is found amongst the differential diagnosis of pancreatic endocrine tumours. We present two clinical cases of ZES recently diagnosed in our centre. Case reportsCase report 1. This is a 50-year-old female with an 11-year history of epigastralgia and diarrhoea that only improved with proton pump inhibitors (PPIs) with a return of symptoms within days of suspending the medication. The patient was sent for gastroscopy which revealed duodenal erosions (Helicobacter pylori negative). A complete laboratory workup for diarrhoea was ordered, including gastrin levels, which were greater than 1,000 pg/ml (normal value: 0-90 pg/ml) with the patient off PPIs for 1 week. Remaining laboratory tests were normal. Given these results, gastric pH was tested, revealing a value of 1.9. The study was completed with an endoscopic ultrasound (EUS) which was normal. Somatostatin receptor scintigraphy revealed a pathological radiotracer deposit on the lesser curvature of the stomach (Fig. 1A).