Somatostatinomas are tumors originally generated from pancreatic or gastrointestinal tract cells and are expected to produce considerable symptomatology in the majority of the patients. Depending on the specific clinical presentation, somatostatinomas can be classified under two distinguishable categories: secretory, causing the inhibitory syndrome, and non-secretory ones, that remain asymptomatic and may be diagnosed incidentally or lead to enteric obstruction.

Those suffering from tumors that secrete somatostatin initially present with the aforementioned inhibitory syndrome. This entails a multitude of reported symptoms, such as diabetes mellitus that can be exacerbated even to a state of hyperglycemic ketoacidosis, cholelithiasis, and weight loss. Steatorrhea or diarrhea episodes are common and individuals tend to report up to ten foul-smelling stools per day; achlorhydria or hypochlorhydria is a frequent finding but does not usually lead to any remarkable complaint. Hormone-secretory somatostatinomas are primarily found in the pancreas; if they originate from the gastrointestinal tract (GIT), they are mainly large lesions, more than 4 cm [1]. Anorexia, vomiting and abdominal discomfort may co-exist.

With regard to non-secretory, or non-functional, somatostatinomas, they usually arise from the duodenum and manifest with duodenal obstruction, cholelithiasis, abdominal pain, jaundice of obstructive nature and bleeding of the GIT [2]. As a rule, they constitute tumors of a smaller diameter than their secretory counterparts and can even be asymptomatic. At the time of diagnosis, approximately 70% of these lesions will have metastasized to the regional lymph nodes or will have lead to hepatic metastases [3].

Some cases may come with symptoms that do not clearly classify them into one of the two previously mentioned categories; these include a wide variety of manifestations associated with pancreatic cancer and the syndrome is therefore described as mixed.

Some individuals with a somatostatinoma may also exhibit skin lesions characteristic of neurofibromatosis type 1 and symptoms further suggestive of a phaeochromocytoma, as these three medical entities are often concurrent [4] [5] [6].

• Exertional Dyspnea

  The patient presented clinically with epigastric discomfort, marked loss of weight, diarrhea, exertional dyspnea, and chest pain. He flushed intermittently and had occasional tachycardia and hypertension. [jamanetwork.com]

• Upper Abdominal Pain

  A 46-year-old woman with a history of recurrent mild upper abdominal pain and diarrhea for 10 months was admitted to our hospital. [ncbi.nlm.nih.gov]

  Symptoms are non-specific but include upper abdominal pain, abdominal swelling and mass, jaundice, weight loss, nausea and vomiting [ 3 ]. Some patients will present with tumour burden from metastatic disease. [neupsykey.com]

• Early Satiety

  These results suggest that somatostatin analogues may not influence tumor autonomy and that a SRIF response to food may contribute to early satiety in patients with somatostatinoma. [ncbi.nlm.nih.gov]

  satiety, weight loss, malabsorptive diarrhea, gallstones Lung with liver metastasis 3097.8 61.1 14.0 (normal range, 36–179) Chemotherapy (cisplatin and vinblastine) Died of pneumonia and sepsis 22 F 47 Severe hyperglycemia and marked ketoacidosis, and [academic.oup.com]

• Foul Smelling Stool

  Steatorrhea or diarrhea episodes are common and individuals tend to report up to ten foul-smelling stools per day; achlorhydria or hypochlorhydria is a frequent finding but does not usually lead to any remarkable complaint. [symptoma.com]

  Steatorrhea (very foul-smelling stool that floats). Gallstones. Yellowing of the skin and whites of the eyes. Weight loss for no known reason. Too much pancreatic polypeptide may cause: belly pain. an enlarged liver. [ronnyallan.com]

• Rectal Mass

  An initial screening colonoscopy 6 months prior to presentation identified a 5-cm rectal mass that biopsies confirmed as invasive adenocarcinoma. [acgcasereports.gi.org]

• Night Sweats

  The patient initially refused other adjunctive exams but after 2 years she was admitted, presenting with itch, night sweats, severe fatigue, and unintentional weight loss. [ncbi.nlm.nih.gov]

• Skin Lesion

  Some individuals with a somatostatinoma may also exhibit skin lesions characteristic of neurofibromatosis type 1 and symptoms further suggestive of a phaeochromocytoma, as these three medical entities are often concurrent. [symptoma.com]

Diagnosing somatostatinomas requires a multitude of invasive and non-invasive tests. A complete blood count, biochemical profile and somatostatin serum levels (fasting) are the initial steps towards a successful diagnosis. Serum levels of this hormone that exceed 100 pg/ml are indicative of a tumor; patients tend to display a significant increase in these values.

A computerized tomography (CT) scan with intravenous contrast enhancement and magnetic resonance imaging (MRI) are the two radiologic modalities initially employed [7]. They are considered of equal value when assessing the existence of a possible somatostatinoma, with the MRI being deemed superior to a CT scan only in the terms of skeletal and hepatic metastasis detection [8].

Endoscopic ultrasonography (EUS) can aid towards the diagnosis of a somatostatinoma accompanied by potential metastatic tumors in the lymph nodes; its contribution is limited in the illustration of distant metastasis. It also enables the evaluation of gastric pH to confirm hypochlorhydria. Finally, a fine needle aspiration (FNA), guided by ultrasonography, can be performed in order to cytologically analyze the lesion and confirm its type [9] [10].

• Small Bowel Mass

  Case Report A 59-year-old man with a history of neurofibromatosis and recently diagnosed rectal adenocarcinoma presented after a small bowel mass was found on abdominal imaging. [acgcasereports.gi.org]

• Small Liver

  A abdominal/pelvic computed tomography (CT) scan at that time showed cholelithiasis, small liver cysts, a mildly dilated pancreatic duct, and the rectal mass. [acgcasereports.gi.org]

1. House MG, Yeo CJ, Schulick RD. Periampullary pancreatic somatostatinoma. Ann Surg Oncol. 2002;9:869–874.
2. Tanaka S, Yamasaki S, Matsushita H, et al. Duodenal somatostatinoma: a case report and review of 31 cases with special reference to the relationship between tumor size and metastasis. Pathol Int. 2000;50:146–152.
3. Nesi G, Marcucci T, Rubio CA, et al. Somatostatinoma: clinico-pathological features of three cases and literature reviewed. J. Gastroenterol. Hepatol. 2008;23(4):521-6.
4. Mao C, Shah A, Hanson DJ, Howard JM. Von Recklinghausen's disease associated with duodenal somatostatinoma: contrast of duodenal versus pancreatic somatostatinomas. J Surg Oncol. 1995;59:67–73.
5. Doherty GM. Rare endocrine tumours of the GI tract. Best Pract Res Clin Gastroenterol. 2005;19:807–817.
6. Cappelli C, Agosti B, Braga M, et al. Von Recklinghausen's neurofibromatosis associated with duodenal somatostatinoma. A case report and review of the literature. Minerva Endocrinol. 2004;29:19–24.
7. King CM, Reznek RH, Dacie JE, Wass JA. Imaging islet cell tumours. Clin Radiol. 1994;49:295–303.
8. Debray MP, Geoffroy O, Laissy JP, et al. Imaging appearances of metastases from neuroendocrine tumours of the pancreas. Br J Radiol. 2001;74:1065–1070.
9. Stelow EB, Woon C, Pambuccian SE, et al. Fine-needle aspiration cytology of pancreatic somatostatinoma: the importance of immunohistochemistry for the cytologic diagnosis of pancreatic endocrine neoplasms. Diagn Cytopathol. 2005 Aug;33(2):100-5.
10. Mori Y, Sato N, Taniguchi R, et al. Pancreatic somatostatinoma diagnosed preoperatively: report of a case. JOP. 2014 Jan 10;15(1):66-71.