False-Negative Neuroendocrine Tumor Identified With 68 Ga-DOTATOC PET/CT : A Case of Well-Differentiated Somatostatinoma.

ABSTRACT: We report the case of a 25-year-old man who was undergoing follow-up for neurofibromatosis type 1. The man underwent 68 Ga-DOTATOC PET/CT for a suspected well-differentiated duodenal neuroendocrine tumor. This examination did not reveal any significant uptake, whereas complementary 18 F-FDG PET/CT showed moderate 18 F-FDG uptake in the primary tumor as well as the adenopathy. Histology, a well-differentiated duodenal neuroendocrine tumor was confirmed, consistent with the diagnosis of somatostatinoma. Although rare, this well-differentiated neuroendocrine tumor should be kept in mind as a possible source of false-negative somatostatin receptor PET/CT findings.

Imaging of Pancreatic-Neuroendocrine Tumours: An Outline of Conventional Radiological Techniques.

INTRODUCTION: Pancreatic Neuroendocrine Tumours (p-NETs) are an important disease entity and comprise of peptide-secreting tumours often with a functional syndrome. Accounting for a small percentage of all pancreatic tumours, they have a good overall survival rate when diagnosed early, with surgery being curative. The role of nuclear medicine in the diagnosis and treatment of these tumours is evident. However, the vast majority of patients will require extensive imaging in the form of conventional radiological techniques. It is important for clinicians to have a fundamental understanding of the p-NET appearances to aid prompt identification and to help direct management through neoplastic staging. METHODS: This article will review the advantages and disadvantages of conventional radiological techniques in the context of p-NETs and highlight features that these tumours exhibit. CONCLUSION: Pancreatic neuroendocrine tumours are a unique collection of neoplasms that have markedly disparate clinical features but similar imaging characteristics. Most p-NETs are small and welldefined with homogenous enhancement following contrast administration, although larger and less welldifferentiated tumours can demonstrate areas of necrosis and cystic architecture with heterogeneous enhancement characteristics. Prognosis is generally favourable for these tumours with various treatment options available. However, conventional radiological techniques will remain the foundation for the initial diagnosis and staging of these tumours, and a grasp of these modalities is extremely important for physicians.

Coexistence of neurofibromatosis type 1 with multiple malignant neoplasia.

Neurofibromatosis type 1 (NF1, von Recklinghausen disease) is inherited in autosomal dominant way genetic disorder, with an incidence at birth 1:3000. It is one of the most common congenital disorders. It is characterized by café-au-lait spots, neurofibromas, and less common MPTST and gliomas of the optic nerve. It is caused by germline mutations of the NF1 gene, which acts as tumor suppressor. Inactivation of the gene leads to increased activation of the kinase pathways, and in consequence, uncontrolled proliferation of cells. The disease predisposes to the development of both benign and malignant tumors. Malignant tumors, but not related to the nervous system occur in neurofibromatosis quite rare. The aim of the study is a literature review of NF1, with presentation of a patient with NF1 and coexisting numerous tumors: synchronous somatostatinoma and gastrointestinal stromal tumor with metachronous prostate adenocarcinoma and non-small cell lung carcinoma. And attempt to answer the question if there is a common pathway for oncogenesis of these four tumors.

Combined presence of multiple gastrointestinal stromal tumors along with duodenal submucosal somatostatinoma in a patient with neurofibromatosis type 1.

Neurofibromatosis type-1 (NF-1) is an autosomal dominant disorder, with increased risk of developing benign and malignant tumors of the gastrointestinal tract (GIT). However, the synchronous presence of multiple GIT stromal tumors and duodenal submucosal somatostatinoma, like in this 50-year-old female NF-1 patient, is very rare. She presented with hematemesis, malena, along with multiple neurofibromas all over the body. Thorough radiological and peroperative work-up revealed multiple ulcerated submucosal and serosal nodules in the proximal small intestine. Histological work-up revealed diagnosis of a duodenal submucosal somatostatinoma with multifocal serosal gastrointestinal stromal tumors. This case is being reported to highlight the rare coincidence of multiple GIT tumors in an NF-1 patient.

Somatostatin-Immunoreactive Pancreaticoduodenal Neuroendocrine Neoplasms: Twenty-Three Cases Evaluated according to the WHO 2010 Classification.

BACKGROUND/OBJECTIVE: Neuroendocrine neoplasms of the pancreas and duodenum with predominant or exclusive immunoreactivity for somatostatin (pdSOMs) are rare, and knowledge about tumour biology, treatment, survival and prognostic factors is limited. This study aims to describe clinical, pathological and biochemical features as well as treatment and prognosis of pdSOMs. DESIGN: Twenty-three patients with pdSOM (9 duodenal, 12 pancreatic and 2 unknown primary tumours) were identified from our prospective neuroendocrine tumour database, and data according to the study aims were recorded. RESULTS: Among the 9 patients with duodenal SOM, the male/female ratio was 4/5. All males and 1 female had neurofibromatosis type 1. Seven patients had stage 1A/B and 2 had stage 2B disease. The Ki-67 index was 1-5% (median 2%). Plasma somatostatin was elevated in the patients with 2B disease. Of the 14 patients with pancreatic SOM or an unknown primary tumour, the male/female ratio was 2/12. One male had multiple endocrine neoplasia type 1. Five had stage 1A/2B and 9 had stage 4. The Ki-67 index was 1-40% (median 7%). Plasma somatostatin was elevated in 7 patients. Patients reported symptoms related to the somatostatinoma syndrome, but none fulfilled the criteria for a full syndrome. Primary tumour in the pancreas, metastatic disease at diagnosis and higher tumour grade were all associated with significantly poorer survival. CONCLUSION: None of the patients with pdSOM presented with the full somatostatinoma syndrome. Prognostic factors are localisation of the primary tumour, dissemination and tumour grade. A Ki-67 index of 5% may discriminate the course of the disease.

Pancreatic and peripancreatic somatostatinomas.

BACKGROUND: Somatostatinomas are rare neuroendocrine tumours with an annual incidence of 1 in 40 million. They arise in the pancreas or periampullary duodenum. Most are clinically non-secretory and do not cause the somatostatinoma syndrome. Many are metastatic at presentation and their management is typically multimodal. CASE HISTORIES: Four cases of somatostatinoma are described. Two patients with periampullary disease presented with biliary obstruction, one with frank jaundice and one with incidental bile duct obstruction on investigation of hepatitis B. Each patient had type 1 neurofibromatosis and resection of the somatostatinoma by means of a pylorus-preserving proximal pancreaticoduodenectomy has resulted in long-term survival. Another two patients with metastatic pancreatic somatostatinomas presented with abdominal pain. Contrasting management illustrates current treatment strategies that are dependent in part on the distribution of the disease. DISCUSSION: The pathophysiology, presentation, clinical associations and role of diagnostic imaging are discussed for periampullary and pancreatic neuroendocrine tumours. Operative treatment has an important role in both the curative and palliative settings in conjunction with appropriate medical treatments and these are described. Management options depend on the extent of the disease and the cases are used to illustrate the rationale of such strategies.

Short-term results of 42 endoscopic ampullectomies: a single-center experience.

OBJECTIVE: Benign lesions of the major papilla are rare but raise the problem of their medical care. We studied the efficacy, safety, and histology of the endoscopic ampullectomy. PATIENTS AND METHODS: Forty-two endoscopic resections of the major papilla were undertaken in 23 males and 19 females of a mean age of 63. Five patients (12%) presented with a familial adenomatous polyposis. The assessment of resectability included preoperative histology, and endoscopic ultrasound (EUS) in 26 patients (62%) always showing intra-mucosal lesion. The resection was performed with a duodenoscope, using a diathermic loop with a pure current section. RESULTS: The resection was realized in one piece for 34 patients, in 2-4 fragments for 8 patients. A plastic pancreatic stent was inserted in 26 patients (62%), a plastic biliary stent in 10 patients (24%). There were no deaths but nine complications (21%): six acute pancreatitis (four patients with a pancreatic stent, contrary to the literature), three delayed gastrointestinal bleeding. The final histological result was fibrosis and inflammatory tissue in 7 patients, low-grade dysplasia in 20 patients, high-grade dysplasia or in situ carcinoma in 10 patients, invasive adenocarcinoma in 1 patient, and somatostatinoma in 2 patients (concordance of 72% with the initial histology). The resection was complete in 39 patients (93%). Three patients had additional surgery because of positive margin of resection or bad histology criteria. The median of follow-up in 33 patients with a complete resection was of 15 months, and we did not note any recurrence in 29 patients (88%). CONCLUSION: Endoscopic ampullectomy is an efficient treatment for superficial lesions of the papilla, despite a significant but rarely severe morbidity. Preoperative EUS is mandatory, preoperative histology is advisable. Long-term follow-up is necessary.

Pancreatic somatostatinoma manifested as severe hypoglycemia.

Somatostatinoma is a rare somatostatin-producing endocrine tumor, probably malignant. Due to its nonspecific symptoms such as vague abdominal pain, weight loss, or occult clinical features, misdiagnosis occurs. We report a case of pancreatic somatostatinoma with severe hypoglycemia. The patient had experienced severe hypoglycemic attacks for 11 months periodically. Contrast computed tomography scan revealed an isodensity mass about 2 cm in the head of the pancreas. Ultimately, a local excision was carried out as the tumor was located exactly on the surface of the pancreas. Somatostatinoma was established after immunohistochemical technique. The patient led a normal life without any complaint at 1 year follow-up.

A large functional somatostatinoma in the pancreatic tail: atypical CT appearances.

Somatostatinomas are extremely rare endocrine tumors, and those with diameters above 2 cm are reported to increase the risk of metastasis significantly. We report a case of a large functional somatostatinoma in the pancreatic tail without metastases. A 46-year-old woman with a history of recurrent mild upper abdominal pain and diarrhea for 10 months was admitted to our hospital. Multiple-phase spiral computed tomography revealed a 10 cm x 8 cm, ill-defined, elliptic mass in the body and tail of the pancreas. There was a slightly heterogeneous enhancement on hepatic arterial phase and isodensity to the pancreatic parenchyma with small dotted necrosis within the middle region of the mass on hepatic portal venous and parenchymal phase, with patent splenic vein, dilated collaterals at the splenic hilum and no dilated pancreatic duct, resembling a diffuse infiltration tumor. To the best of our knowledge, this is the first description of multiple-phase spiral computed tomography findings of a functional somatostatinoma in the pancreatic tail and the largest thus far on reported computed tomography, with some differences compared with the previous reports.

Diagnostic usefulness of FDG-PET for malignant somatostatinoma of the pancreas.

A 24-year-old female complaining of diarrhea and back pain was admitted to hospital where a tumor of the pancreatic head was revealed on a computed tomography (CT) scan. Abdominal ultrasonography, CT and celiac angiography revealed a hypervascular lesion on the pancreas. An endocrine tumor, particularly a somatostatinoma, was suspected and hormone levels in the blood were examined. Serum hormone levels were normal, so FDG-PET was performed. An abnormally high accumulation of FDG was detected on the FDG-PET image at the head of the pancreas, and the SUV of the lesion was 3.2, so the mass was considered to be malignant on FDG-PET. Pylorus-preserving pancreatoduodenectomy was performed with a preoperative diagnosis of malignant endocrine tumor. The resected specimen revealed a massive, yellowish-white tumor of the pancreas head measuring 50x 45x38mm. Histologically, the tumor was a malignant islet-cell tumor, and immunohistochemically the tumor stained with an anti-somatostatin antibody, but not with antibodies against glucagons, insulin or vasoactive intestinal polypeptide. The patient was discharged after the operation and has remained well without recurrence for 5 years. Liver metastatic tumors, however, appeared 6 years after the operation.

Incidental small ampullary somatostatinoma treated with ampullectomy 2 years after diagnosis.

Somatostatinomas are rare tumors; ampullary somatostatinomas are very rare. We report a case of a small pure somatostatin-producing neuroendocrine tumor of ampulla of Vater in a 54-year-old woman with neither neurofibromatosis nor somatostatinoma syndrome, "incidentally" discovered during an abdominal computed tomography. 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. The size of the tumor (1.5 cm) and the other radiologic findings had not changed since the abdominal CT scan 2 years before. The somatostatin, gastrin, glucagons, serotonin, vasoactive intestinal peptide, dopamine, norepinephrine, epinephrine, and calcitonin plasma levels were normal. ERCP-obtained biopsies revealed a neuroendocrine tumor with psammoma bodies; immunohistochemical profile was positive for chromogranin and somatostatin. The patient underwent surgery; intraoperative histologic examination of lymph nodes sampling of perihepatic and periduodenal lymph nodes was negative for metastasis. We performed, therefore, a transduodenal ampullectomy. The patient continues to do well at 3 years' follow-up with no evidence of local or distance recurrence of disease.

Duodenal somatostatinoma: clinical and immunohistochemical patterns--difficult differential diagnosis in regard to gangliocytic paraganglioma: report of a case.

The authors report a large duodenal somatostatinoma, a very rare tumor entity. A 8.5 cm globular mass in the area of the unicate process of the pancreas was detected in a 45 year old caucasian female by computerized tomography. The patient had only mild complaints. Initial treatment consisted of right pancreatectomy with preservation of the pylorus. Histological evaluation rendered a diagnosis of low-grade malignant neuroendocrine carcinoma with expression of somatostatin, respectively of somatostatinoma arising in the duodenum and infiltrating into the pancreas. 26 months after the initial surgery liver and lymph node metastases were detected and surgically removed. This case confirms that duodenal somatostatinomas are very difficult to diagnose preoperatively because of unspecific symptoms. Most duodenal somatostatinomas are found incidentally. Treatment of choice is radical surgical resection with a possible cure in early stages of the disease. Even a large tumor as ours is resectable with negative surgical margins. Management of recurrent or metastatic disease is also surgical. Additional chemotherapy and supportive care may be beneficial for the patient.

Malignant duodenal somatostatinoma presenting in association with von Recklinghausen disease.

Somatostatinomas are extremely rare periampullary malignant neuroendocrine tumors that may be associated with von Recklinghausen disease or type-I neurofibromatosis. Duodenal somatostatinomas are distinguished from pancreatic somatostatinomas by their frequent association with type-I neurofibromatosis and typically absence of somatostatinoma syndrome. We report a very rare and atypical case of malignant duodenal somatostatinoma presenting with somatostatinoma syndrome in association with type-I neurofibromatosis.

Somatostatinoma of the papilla of Vater with multiple gastrointestinal stromal tumors in a patient with von Recklinghausen's disease.

We report a case of somatostatinoma of the papilla of Vater with multiple gastrointestinal stromal tumors in a patient with von Recklinghausen's disease (VRD). A 64-year-old woman who had had recurrent attacks of acute pancreatitis and cholangitis was found, on gastroduodenal endoscopy, to have a tumor of the papilla of Vater and multiple submucosal tumors of the stomach and duodenum. Numerous submucosal tumors were observed in the stomach, duodenum, and jejunum, and total excision of the papilla of Vater and resection of the duodenal and jejunal submucosal tumors was performed. The tumor of the papilla of Vater showed the histologic appearance of a dense proliferation of tumor cells in acinar form, from the duodenal mucosa to the muscle layer, and psammoma bodies were revealed within the tumor. Immunohistologically, the tumor cells were intensely positive for somatostatin. The submucosal tumors of the duodenum and jejunum were negative for smooth muscle actin, s-100, and neuron-specific enolase (NSE), and positive for CD34 and c-kit, and they were diagnosed as gastrointestinal stromal tumors (GISTs) according to the strict definition. The only 25 cases of papilla of Vater somatostatinoma associated with VRD to have been reported in the English-language literature since 1982 are reviewed, as well as our own case.