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  • • Diabetes mellitus (usually mild)

    • Diarrhea

    • Malabsorption

    • Dilation of the gallbladder (usually with cholelithiasis)

    • Hypochlorhydria

    • Weight loss

Epidemiology

  • • Account for 1-2% of pancreatic islet cell tumors

    • The syndrome results from secretion of somatostatin by an islet cell tumor of the pancreas

    • Most tumors are malignant and accompanied by hepatic, regional lymph node, and bone metastases

    • Mean age at presentation is 50 years

    • Men and women are affected equally

    • The lesion is usually large and readily demonstrated by CT scan

Symptoms and Signs

  • • Diarrhea

    • Steatorrhea

    • Weight loss

Laboratory Findings

  • • Increased plasma level of somatostatin

Imaging Findings

  • • The lesion is usually large and readily demonstrated by CT scan

    • Abdominal US may show gallbladder dilation with cholelithiasis

  • • The diagnosis may be made by recognizing the clinical syndrome and measuring increased concentrations of somatostatin in the serum

    • Small somatostatin-rich tumors of the duodenum or ampulla of Vater have also been reported, but none of these lesions have been associated with high serum levels of somatostatin or the clinical syndrome

Rule Out

  • • Other islet cell tumors of the pancreas

    • Other causes of diarrhea and malabsorption

  • • Serum somatostatin level

    • CT scan for localization and staging

    • Endoscopy and endoscopic ultrasound for small tumors

When to Admit

  • • Severe symptoms

Surgery

  • • Enucleation is inappropriate for these tumors and a pancreaticoduodenectomy should be performed for lesions located in the head of the pancreas

Indications

  • • All patients with technically resectable lesions

    • Debulking of hepatic metastases is indicated for relief of symptoms

Contraindications

  • • Technically unresectable

Medications

  • • Chemotherapy with streptozocin, dacarbazine, or doxorubicin for unresectable tumors

Prognosis

  • • When the disease is localized, resection is able to cure about 50% of patients

References

Soga J, Yakuwa Y. Somatostatinoma/inhibitory syndrome: a statistical evaluation of 173 reported cases as compared to other pancreatic endocrinomas. J Exp Clin Cancer Res. 1999;18:13.  [PubMed: 10374671]
Jensen RT: Carcinoid and pancreatic endocrine tumors: recent advances in molecular pathogenesis, localization, and treatment. Curr Opin Oncol 2000;12:368.  [PubMed: 10888424]
Somogyi L, Mishra G: Diagnosis and staging of islet cell tumors of the pancreas. Curr Gastroenterol Rep 2000;2:159.  [PubMed: 10981018]
Tanaka S 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.  [PubMed: 10792774]

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