Malignant somatostatinoma presenting with diabetic ketoacidosis and inhibitory syndrome: pathophysiologic considerations.

OBJECTIVE: To describe a patient with diabetic ketoacidosis secondary to a malignant somatostatinoma. METHODS: We present the clinical, laboratory, radiologic, and pathologic findings of a patient with diabetic ketoacidosis secondary to a malignant somatostatinoma. We also review the potential effects of somatostatin on glucose homeostasis and discuss the underlying pathophysiologic mechanisms. RESULTS: A 30-year-old woman presented with diabetic ketoacidosis and had a malignant somatostatinoma with hepatic, bone, and lymph node metastasis. She exhibited features of somatostatinoma "inhibitory syndrome" characterized by mild nonketotic hyperglycemia, hypochlorhydria, cholelithiasis, steatorrhea, anemia, and weight loss. In these tumors, the absence of ketoacidosis is thought to arise from the somatostatin-induced simultaneous suppression of the secretion of insulin and glucagon. The patient's primary tumor could not be located. CONCLUSIONS: Diabetic ketoacidosis may occur in somatostatinomas. The secretion of larger molecular weight forms of somatostatin from the tumor may contribute to the ketogenesis.

Mixed endocrine somatostatinoma of the ampulla of vater associated with a neurofibromatosis type 1: a case report and review of the literature.

CONTEXT: Mixed endocrine tumors are double neoplasms with both glandular and endocrine components; these tumors are rare, especially those arising in the ampulla of Vater. Ampullary somatostatinomas are classically associated with neurofibromatosis type 1. We herein describe the first reported case of a mixed endocrine somatostatinoma of the ampulla of Vater associated with neurofibromatosis type 1; we also present a review of the literature of the 7 mixed endocrine tumors of the ampulla which have been reported so far. CASE REPORT: A 49-year-old woman presented with atypical abdominal pain. Endoscopic examination revealed a tumor involving the ampulla of Vater and a CT scan identified stenoses of both the distal common bile duct and the main pancreatic duct. A pancreaticoduodenectomy was performed and pathological examination revealed two tumor components, exocrine (high grade adenoma with infiltrative adenocarcinoma) and endocrine (expressing somatostatin hormone) with lymph node metastases originating from both types. The patient was treated with adjuvant chemotherapy and has had no recurrence for 3 years. DISCUSSION: In ampullary somatostatinomas, psammoma bodies are pathognomonic and chromogranin A is rarely expressed: these features should alert the pathologist to an association with neurofibromatosis type 1. The management of patients with mixed tumors is challenging. The treatment of choice is surgery, and adjuvant chemotherapy should be adapted to the most aggressive component, i.e. the exocrine one. CONCLUSION: Because of their rarity, the diagnosis of ampullary mixed endocrine tumors is difficult. Our case points out the characteristic features of these neoplasms and their possible association with neurofibromatosis type 1.

Ampullary somatostatinomas and jejunal gastrointestinal stromal tumor in a patient with Von Recklinghausen's disease.

Von Recklinghausen's disease is an autosomal dominant hereditary disease associated with a wide number of neoplasms. We report a case of a 47-year-old Caucasian male affected by Von Recklinghausen's disease who developed a malignant somatostatinoma of the papilla major and minor associated with jejunal gastrointestinal stromal tumour with uncertain behaviour. At laparotomy, multiple hepatic metastases were evident. Whipple pancreaticoduodenectomy, jejunal resection, extensive lymphadenectomy and multiple hepatic wedge resections were performed. The patient was alive without recurrence after 24 mo. This is the fourth case reported in the world literature of a patient with Von Recklinghausen's disease associated with periampullary somatostatinomas and jejunal stromal tumor. In patients with Von Recklinghausen's disease who complain of gastrointestinal symptoms, a high suspicion index for periampullary endocrine tumours and/or gastrointestinal stromal tumour is required. An aggressive surgical approach seems to give long term survival also in metastatic patients.

Duodenal somatostatinoma associated with diabetic ketoacidosis presumably caused by somatostatin-28 hypersecretion.

CONTEXT: Extrapancreatic somatostatinoma is very rare and clinically distinguished from its pancreatic counterpart because somatostatinoma syndrome with mild diabetes is rare in extrapancreatic somatostatinoma because of poor secretion of somatostatin. Moreover, because somatostatin inhibits the secretion of insulin and glucagon simultaneously, true diabetic ketoacidosis (DKA) seldom ensues. PATIENT: A 23-yr-old woman presented with DKA and an abdominal mass. A computed tomography scan showed a huge, encapsulated mass in a duodenal submucous portion. A high circulating level of somatostatin was detected (67.2 pmol/liter; reference range, 0.6-7.3 pmol/liter). INTERVENTION: The tumor mass was successfully removed with Whipple's procedure, and the patient gradually recovered both clinically and biochemically. RESULTS: Immunohistochemical staining of the tumor tissue exhibited diffusely positive for somatostatin and somatostatin-28 but negative for insulin, glucagon, calcitonin, serotonin, and S-100. CONCLUSION: As far as we know, this is the first case report of gastrointestinal somatostatinoma associated with DKA.