Somatostatinoma: causes, symptoms, diagnosis, treatment

For the first time somatostatinoma (sigma-cell tumor of the islets of Langerhans) has been described relatively recently - in 1977, therefore the idea of a symptom complex characterizing this disease has not yet been formed. Tumors, in most cases carcinomas, originate from somatostatin-forming D-cells. Metastasis occurs mainly in the liver. Some authors, because of the heterogeneity of the symptoms, believe that there is no clear clinical syndrome of somatostatinoma at all. At the present time in the literature are described a little more than 20 patients with somatostatin-secreting tumors of the pancreas and duodenum. Undoubtedly, surgeons have faced these neoplasms earlier in operations with cholelithiasis, but only now it has become clear that this is not an accidental combination. Along with cholelithiasis, somatostatinomas show diabetes, diarrhea or steatorrhea, hypochlorhydria, anemia, weight loss.

Apparently, many manifestations are the result of the blocking action of somatostatin on the enzymatic function of the pancreas and the secretion of other hormones in the islets of Langerhans, so this symptom complex is sometimes called an "inhibitory syndrome".

Most of the secretions described by somatostatin were polyhormonal in nature. It is likely that this is one of the reasons for the heterogeneity of the clinical manifestations of the disease.

Symptoms that occur with somatostatinome reflect the known effects of somatostatin. Pathological glucose tolerance is associated with inhibition of the release of insulin, not offset by a simultaneous decrease in glucagon secretion. The increased frequency of cholelithiasis is largely due to the contractile capacity of the gallbladder, which is reduced by the excessively produced somatostatin (a large atonic gallbladder is defined in patients). Stethorrhea is explained as a result of insufficient exocrine pancreatic function and impaired intestinal absorption. Gastric hypochlorhydria is a consequence of the inhibitory effect of somatostatin on acid-forming parietal cells and also on the release of gastrin by the mucous membrane of the antrum of the stomach.

The diagnosis of somatostatinoma is based on the evidence of an elevated peptide level in the plasma. In doubtful cases, a provocative trial with tolbutamide should be conducted, which stimulates the release of somatostatin.

As a rule, after the operation, repeated courses of cytostatic therapy with streptozotocin and 5-fluorouracil are required.

[1], [2], [3], [4], [5], [6], [7]