Malignant somatostatinoma: clinical features and metabolic studies

Clinicopathological Data and Treatment Modalities for Pancreatic Somatostatinomas

BACKGROUND/AIM

Somatostatinomas (SSomas) constitute a rare neuroendocrine tumor. The purpose of this study was to evaluate the current published literature about pancreatic SSomas and report epidemiologic and clinicopathologic data for this entity.

PATIENTS AND METHODS

A combined automated and manual systematic database search of the literature was performed using electronic search engines (Medline PubMed, Scopus, Ovid and Cochrane Library), until February 2020. Statistical analysis was performed using the R language and environment for statistical computing.

RESULTS

Overall, the research revealed a total of 36 pancreatic SSoma cases. Patient mean age was 50.25 years. The most common pancreatic location was the pancreatic head (61.8%). The most frequent clinical symptom was abdominal pain (61.1%). Diagnostic algorithm most often included Computed Tomography and biopsy; surgical resection was performed in 28 cases. Out of the 36 cases, 22 had been diagnosed with a metastatic tumor and metastasectomy was performed in 6 patients with a worse overall survival (OS) (p=0.029). In total, OS was 47.74 months.

CONCLUSION

Patients with metastatic disease did not benefit from metastasectomy, but the sample size was small to reach definite conclusions. However, further studies with longer follow-up are needed for a better evaluation of these results.

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.

New and emerging syndromes due to neuroendocrine tumors

Neuroendocrine tumors (NETs) are rare, slow-growing neoplasms characterized by their ability to store and secrete different peptides and neuroamines. Some of these substances cause specific clinical syndromes whereas others are not associated with specific syndromes or symptom complexes. NETs usually have episodic expression that makes diagnosis difficult, erroneous, and often late. For these reasons a high index of suspicion is needed, and it is important to understand the pathophysiology of each tumor to decide which biochemical markers are more useful and when they should be used.

The diagnosis and medical management of advanced neuroendocrine tumors

Neuroendocrine tumors (NETs) constitute a heterogeneous group of neoplasms that originate from endocrine glands such as the pituitary, the parathyroids, and the (neuroendocrine) adrenal, as well as endocrine islets within glandular tissue (thyroid or pancreatic) and cells dispersed between exocrine cells, such as endocrine cells of the digestive (gastroenteropancreatic) and respiratory tracts. Conventionally, NETs may present with a wide variety of functional or nonfunctional endocrine syndromes and may be familial and have other associated tumors. Assessment of specific or general tumor markers offers high sensitivity in establishing the diagnosis and can also have prognostic significance. Imaging modalities include endoscopic ultrasonography, computed tomography and magnetic resonance imaging, and particularly, scintigraphy with somatostatin analogs and metaiodobenzylguanidine. Successful treatment of disseminated NETs requires a multimodal approach; radical tumor surgery may be curative but is rarely possible. Well-differentiated and slow-growing gastroenteropancreatic tumors should be treated with somatostatin analogs or alpha-interferon, with chemotherapy being reserved for poorly differentiated and progressive tumors. Therapy with radionuclides may be used for tumors exhibiting uptake to a diagnostic scan, either after surgery to eradicate microscopic residual disease or later if conventional treatment or biotherapy fails. Maintenance of the quality of life should be a priority, particularly because patients with disseminated disease may experience prolonged survival.

Metastatic Psammomatous Somatostatinoma of the Pancreas Causing Severe Ketoacidotic Diabetes Cured by Surgery

A case of somatostatin-producing pancreatic tumor associated with severe insulin-dependent diabetes mellitus and ketoacidotic coma is reported. The tumor, a 10-cm expansile mass arising from the pancreatic tail of a 70-yr-old woman, was first detected by ultrasonography, performed because of abdominal pain, and subsequently confirmed by computed tomography and fine-needle tumor aspiration. Pathologic investigation showed a predominantly solid-trabecular structure with scattered microacini and psammomatous bodies. A large proportion of tumor cells expressed somatostatin and/or calcitonin. Following resection of the primary tumor and three peripancreatic lymph nodes with metastases, the patient recovered rapidly from her diabetic syndrome and remained in substantially good health during a subsequent 8-yr follow-up period, without evidence of tumor recurrence.

Clinical spectrum of hyperglucagonemia associated with malignant neuroendocrine tumors

OBJECTIVE

To review the clinical features associated with hyperglucagonemia in malignant neuroendocrine tumors.

MATERIAL AND METHODS

We retrospectively reviewed the medical records of patients with hyperglucagonemia encountered at our institution from Oct. 17, 1988, through February 1993 who had a fasting serum glucagon level of at least 120 pg/mL (twice the normal value). The 71 study patients also had no evidence of a secondary cause of hyperglucagonemia and had pathologic confirmation of a neuroendocrine tumor.

RESULTS

The study group consisted of 46 men and 25 women with a median age of 57 years. Two patients had multiple endocrine neoplasia. Forty-nine patients had biochemically polyfunctional tumors, and 22 had hyperglucagonemia only. The most common initial symptoms were weight loss, abdominal pain, diarrhea, nausea, peptic ulcer disease, diabetes, and necrolytic migratory erythema (NME). Diabetes eventually developed in 25 patients and was associated with NME in 11. The highest median serum glucagon values occurred in patients with the glucagonoma syndrome or insulinomas, and the lowest median values were in those with carcinoid syndrome, Zollinger-Ellison syndrome, or diabetes without NME. Fasting glucagon and glucose measurements were not correlated. The most common hormonal syndromes were the Zollinger-Ellison syndrome and the glucagonoma syndrome. All the neuroendocrine tumors were malignant. Several methods of treatment, including surgical debulking, chemotherapy, somatostatin, and hepatic artery embolization, were used. Death occurred in 29 patients at a median of 2.79 years after diagnosis; 42 patients were alive at a median of 2.86 years after diagnosis.

CONCLUSION

A mild degree of hyperglucagonemia can commonly be associated with multifunctional neuroendocrine tumors. The glucagonoma syndrome occurs in a few patients with malignant neuroendocrine tumors and hyperglucagonemia and is associated with very high serum glucagon levels. The correlation between serum glucagon levels and the development of diabetes is limited, and other factors such as insulin may be more important than hyperglucagonemia in the development of diabetes.

The glucagonoma syndrome. Clinical and pathologic features in 21 patients

The glucagonoma syndrome is a rare disorder characterized by weight loss, necrolytic migratory erythema (NME), diabetes, stomatitis, and diarrhea. We identified 21 patients with the glucagonoma syndrome evaluated at the Mayo Clinic from 1975 to 1991. Although NME and diabetes help identify patients with glucagonomas, other manifestations of malignant disease often lead to the diagnosis. If the diagnosis is made after the tumor is metastatic, the potential for cure is limited. The most common presenting symptoms of the glucagonoma syndrome were weight loss (71%), NME (67%), diabetes mellitus (38%), cheilosis or stomatitis (29%), and diarrhea (29%). Although only 8 of the 21 patients had diabetes at presentation, diabetes eventually developed in 16 patients, 75% of whom required insulin therapy. Symptoms other than NME or diabetes mellitus led to the diagnosis of an islet cell tumor in 7 patients. The combination of NME and diabetes mellitus led to a more rapid diagnosis (7 months) than either symptom alone (4 years). Ten patients had diabetes mellitus before the onset of NME. No patients had NME clearly preceding diabetes mellitus. Increased levels of secondary hormones, such as gastrin (4 patients), vasoactive intestinal peptide (1 patient), serotonin (5 patients), insulin (6 patients, clinically significant in 1 only), human pancreatic polypeptide (2 patients), calcitonin (2 patients) and adrenocorticotropic hormone (2 patients), contributed to clinical symptoms leading to the diagnosis of an islet cell tumor before the onset of the full glucagonoma syndrome in 2 patients. All patients had metastatic disease at presentation. Surgical debulking, chemotherapy, somatostatin, and hepatic artery embolization offered palliation of NME, diabetes, weight loss, and diarrhea. Despite the malignant potential of the glucagonomas, only 9 of 21 patients had tumor-related deaths, occurring an average of 4.91 years after diagnosis. Twelve patients were still alive, with an average age follow-up of 3.67 years.

Von Recklinghausen's disease associated with duodenal somatostatinoma: contrast of duodenal versus pancreatic somatostatinomas

A case of Von Recklinghausen's disease with duodenal somatostatinoma is reported. A search of the world's literature revealed 27 patients with Von Recklinghausen's disease associated with an immunohistologically proved duodenal somatostatinoma. Twenty-nine cases of duodenal somatostatinoma not associated with Von Recklinghausen's disease and 32 cases of pancreatic somatostatinomas have been identified for comparison. While their histology may be similar in many respects, the duodenal and pancreatic somatostatinomas show significant differences, especially in hormonal and growth behaviors. In contrast to its pancreatic counterpart, the duodenal somatostatinoma is frequently associated with Von Recklinghausen's disease, is seldom associated with a recognizable "somatostatin syndrome," often contains psammoma bodies, and is less frequently associated with demonstrable metastases at the time of operation.

Pancreatic somatostatinoma: a case report and review of the literature

A 56-year-old man underwent distal pancreatectomy, splenectomy, and partial resection of the splenic flexure of the colon because of tumor in the tail of pancreas and the splenic hilus. The patient presented with symptoms of general malaise, anorexia, weight loss, mild diarrhea, and borderline diabetes mellitus, although there was no cholelithiasis. The diagnosis remained unclear until immunohistochemical studies of the resected specimen revealed somatostatin and synaptophysin, suggesting a somatostatinoma. Twenty-three reported cases of pancreatic somatostatinoma are reviewed and their clinical features discussed. The role of immunohistochemical studies in the diagnosis of somatostatinoma is described.

Anatomic distribution of pancreatic endocrine tumors

Pancreatic endocrine tumors are grouped together by their common histologic, cytochemical, and ultrastructural features. Although useful conceptually, this paradigm has been unable to predict the anatomic location of different tumor types. Successful surgical excision of these tumors would be facilitated by an improved understanding of their anatomic distribution. Based on the available data, a bimodal distribution of pancreatic endocrine tumors was identified. Cluster 1 (gastrinomas, pancreatic polypeptide (PP)-secreting tumors, somatostatinomas) had 75% of tumors to the right of the superior mesenteric artery, whereas cluster 2 (insulinoma, glucagonoma) had 75% of tumors to the left of the superior mesenteric artery (p less than 0.05). This distribution is similar to that distribution predicted based on the volume density of the corresponding islet cells for insulinoma, glucagonoma, and PP-secreting tumors, but not for somatostatinoma. These findings suggest that pancreatic endocrine tumors are derived from similar cytologic precursors as pancreatic islet cells, and their distribution may be a consequence of embryologic development from either the ventral (cluster 1) or dorsal (cluster 2) pancreatic buds.

Somatostatinoma: a case report and review of the literature

Somatostatinomas are rare endocrine tumors that were first described in 1977. In addition to the present case report, there have been 31 cases reported in the literature. We have reviewed the literature to integrate the symptoms, physical findings, diagnostic tests, treatment, and length of survival of these patients. Although the symptoms that occurred in the majority of cases were those that are seen in most patients with intra-abdominal neoplasms, symptoms relating to the presence of excess circulating somatostatin--diabetes, maldigestion, and cholelithiasis--were frequently seen. Physical findings and the results of diagnostic tests were usually nonspecific. The majority of the patients underwent radical surgical procedures (Whipple procedure or pancreatic resection). The pancreas was the most frequent site of involvement (21/31 cases), but primaries in the duodenum, ampulla of Vater, cystic duct, and jejunum have been described as well. Metastases were most frequently seen in the liver and lymph nodes. Chemotherapeutic agents were administered to 10 patients, usually as adjuvant therapy, and appear to be useful in treating recurrent and metastatic disease. The one-year survival of these patients is 48%, which is better than that for patients with carcinoma of the pancreas or biliary tree. Therefore, it is important that the diagnosis of somatostinoma be made so that the patient may be treated accordingly and followed by serial somatostatin levels for evidence of metastasis or recurrent disease.

Malignant somatostatinoma presenting with diabetic ketoacidosis

High circulating levels of somatostatin (SRIF) were detected in a patient with a metastatic tumour after development of diabetic ketoacidosis (DKA). Fasting insulin and C-peptide levels were markedly suppressed, but plasma glucagon was not suppressed below normal. Progressive cachexia ensued; at autopsy a poorly differentiated non-small cell neuroendocrine carcinoma metastatic to liver was found. Small gallstones were noted. Electron microscopy of tumour tissue showed neurosecretory granules and tonofilament bundles. Immunohistochemical staining of tumour cells was diffusely positive for carcinoembryonic antigen, bombesin-like immunoreactivity, and calcitonin with focal immunoreactivity for SRIF, serotonin, neuron-specific enolase, chromogranin, and epithelial membrane antigen. Column chromatography of plasma and tumour extract revealed five or more peaks of material with SRIF-like immunoreactivity (SRIF-LI): predominantly SRIF-28 and intermediates in tumour extract, and SRIF-14 and an intermediate between SRIF-28 and SRIF-14 in plasma, DKA in this case of somatostatinoma syndrome may reflect differential effects of tumour production of larger molecular weight SRIF forms on insulin and glucagon secretion.

Comparative diagnostic value of the calcium-pentagastrin test versus the tolbutamide test in a patient with a somatostatinoma

We describe a patient with a small somatostatinoma of the papilla of Vater without clinical evidence for diabetes mellitus, diarrhea, steatorrhea, or cholelithiasis, showing normal plasma basal levels for somatostatinlike immunoreactivity. The diagnosis was based on histologic and immunohistochemical analysis of tumor tissue and hypersomatostatinemia induced by the calcium-pentagastrin test. Before removal of the tumor both diagnostic tests recommended for the detection of a somatostatinoma, a tolbutamide test and a calcium-pentagastrin test, were performed. Whereas the calcium-pentagastrin test provoked a markedly elevated plasma somatostatin level in association with a depressed plasma neurotensin level, the tolbutamide test surprisingly did not. After removal of the tumor the calcium-pentagastrin test no longer induced hypersomatostatinemia. Further studies are needed to determine whether the calcium-pentagastrin test is a more reliable diagnostic test than the tolbutamide test in somatostatinomas with normal plasma basal levels.

Successful treatment of glucagonoma-related necrolytic migratory erythema with dacarbazine

A 63-year-old man with a glucagonoma syndrome is described. The diagnosis was confirmed by necrolytic migratory erythema, which is the most distinctive feature of the clinical syndrome. There was no chance of operative resection of the tumor because of liver metastases at the time of diagnosis. The patient was treated with dacarbazine. During this treatment the skin lesions disappeared completely.

Somatostatinoma of the cystic duct

An unusual tumor of the cystic duct in a 28-year-old woman is described. The patient presented with a painful distended gallbladder due to a small tumor occluding the cystic duct. Microscopically the tumor cells showed a nesting pattern suggestive of endocrine differentiation, but contained numerous lipid vacuoles and were argentaffin and argyrophil negative. Ultrastructurally, there were relatively few dense granules measuring 135 to 475 nm. Immunoperoxidase staining showed that the tumor cells contained somatostatin but did not contain immunoreactive ACTH, gastrin, calcitonin, glucagon, insulin, parathyroid hormone, or carcinoembryonic antigen. To the authors' knowledge, this is the first reported somatostatinoma occurring in the extrahepatic biliary tract.

Pancreatic somatostatinoma

A 66 year old woman was admitted for right hypochondriac pain and an abdominal tumor. A tumor of the pancreatic head with duodenal infiltration and liver metastases was found by laparotomy, and pancreaticoduodenectomy was performed. In addition, there was associated cholelithiasis and a goiter. Histopathologically, a tumor of the islets of Langerhans was suspected. The tumor tissue was positive by the Hellman-Hellerström silver impregnation method, and electron microscopy confirmed the presence of secretory granules similar to D cells. The tumor tissue contained a large quantity of somatostatin (1.3 micrograms/g). Finally, the diagnosis of somatostatin-producing tumor originating in the pancreas was made.

Somatostatinoma syndrome. Clinical, morphological and metabolic features and therapeutic aspects

A case of somatostatinoma syndrome in a 30-year-old woman is presented. Basal levels of growth hormone and of pancreatic and gastric hormones were reduced and the response of growth hormone, insulin and C-peptide to stimuli such as arginine, glucose, glibenclamide and calcium was virtually abolished. Similarly, gastric acid secretion, pancreatic exocrine function and intestinal absorption were significantly reduced. On the other hand, basal and stimulated levels of adrenocorticotropic hormone (ACTH), luteinizing hormone (LH), follicle-stimulating hormone (FSH) and thyroid-stimulating hormone (TSH) were within the normal range. Plasma somatostatin-like immunoreactivity was increased to 600-2,000 pg/ml (normal: 88-140 pg/ml). Immunocytochemical studies demonstrated the presence of somatostatin immunoreactive material in the primary tumour in the head of the pancreas and in the liver metastases. In spite of two courses of chemotherapy with streptozotocin and 5-fluorouracil the patient died due to liver failure 5 months after the first admission to hospital.