Hormone-active pancreatic tumors: causes, symptoms, diagnosis, treatment

Most hormonally active tumors of the digestive system are localized in the pancreas. This is due to the abundance of hormone-competent cells in it, from which such tumors originate. The first report of adenocarcinoma of the pancreatic islets, occurring with symptoms of hypoglycemia (a tumor later called insulinoma), was made in 1927 by RM Welder et al. At present, 7 clinical syndromes are known, caused by the development of pancreatic tumors that produce various hormones.

The cells from which hormone-producing tumors of the pancreas originate belong, according to the concept of F. Feyrter (1938), to the diffuse endocrine system, and according to the hypothesis of A. G. E. Pearse (1966), to the APUD cell system. The term is an acronym for the words Amino Acid Precursor Uptake and Decarboxylation, meaning the ability of cells to capture precursors of biogenic amines from the environment and decarboxylate them. By now, the understanding of the term has changed. The biochemical properties encoded by the letters APUD are not mandatory for APUD cells. Now, the term "APUD system" refers to cell types capable of secreting biologically active amines or polypeptides and proteins and accumulating them in endoplasmic granules with specific ultrastructural and cytochemical properties.

Tumors arising from the cells of the APUD system are called apudomas. They are extremely heterogeneous in structure. Most often, apudomas synthesize products characteristic of normal apudocytes of the corresponding localization - orthoendocrine apudomas, according to R. B. Welbourn (1977). An example is the pancreatic tumor insulinoma. Often, apudomas produce substances that are not inherent in the normal endocrine cells of this organ (paraendocrine apudomas). Thus, there are tumors of the pancreas that produce ACTH and / or ACTH-like substances, which leads to the clinical picture of Cushing's syndrome. Almost simultaneous or sequential development of hormonally active tumors of various organs both inside and outside the digestive tract is possible (multiple endocrine adenomatosis).

Endocrine tumors of the digestive system are named, if possible, according to the hormonal product they produce. In cases where the suspected hormone is not proven or secretion of several hormonal substances by the tumor is assumed, determining the clinical picture of the disease, it is designated descriptively.

Endocrine tumors of the pancreas are found in various parts of it. Clinical manifestations usually occur when the tumor size is more than 0.5 cm. At first, symptoms of metabolic disorders caused by hormonal excess often appear, and only later - clinical manifestations from the affected organ. Endocrine tumors of the pancreas can be benign and malignant. The larger the size of the tumors, the more often they metastasize. Metastases are also mainly hormonally active.

Diagnosis of apudoms includes two tasks: to establish the localization of the tumor, and in the case of damage to the pancreas, to find out its intraorgan location, since this determines the tactics of surgical intervention; to establish the hormonal substance produced by the tumor, which is necessary for adequate conservative treatment.

It became possible to prove the production of a specific hormone by a tumor due to the development and implementation of radioimmune research methods, specific and highly sensitive. When the hormone is secreted by apudoma cells into the blood, its increased content in the plasma can be determined. Immunocytochemical examination of organ biopsies obtained during preoperative biopsy (or intraoperatively) also helps in diagnostics. In some cases, identification of endocrine cells in a tumor is also possible by determining typical secretory granules using electron microscopy.

If a pancreatic tumor is suspected, CT, ultrasound, scintigraphy, selective angiography of the celiac trunk and superior mesenteric artery are used. If the tumor size is 1 cm or more, its location can usually be determined. To clarify the diagnosis, a puncture biopsy of the pancreas is performed under ultrasound or X-ray control during CT, followed by histological and immunocytological examination. In doubtful cases, percutaneous transhepatic catheterization of the veins draining the pancreas - splenic, pancreatoduodenal, superior mesenteric - is performed to clarify the intrapancreatic localization of the endocrine tumor, with blood sampling to determine the concentration of a particular hormone. Great hopes are pinned on endoscopic ultrasound, which has been developed in recent years. Endoscopic retrograde pancreatography is effective only when the tumor leads to changes in the pancreatic duct system (eg, stenosis, obstruction).

Radical treatment is only surgical. A superficially located adenoma, especially if localized in the head of the gland, is enucleated. In case of deeper localization of the tumor, the scope of the operation is increased, resection of the corresponding section of the gland is used, up to partial duodenopancreatectomy. In case of a malignant tumor and impossibility of its radical removal, palliative intervention is performed: to reduce the mass of secreting tissue, the tumor and metastases are removed as completely as possible.

In preoperative management of patients, when the tumor localization has not yet been established, symptomatic drug treatment is prescribed, and inoperable patients and patients with widespread metastases that cannot be removed are additionally given cytostatic therapy.

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