Diagnostics of the pheochromocytoma (chromaffinomas)

The variety of clinical manifestations of fechromocytoma led to the search for the most characteristic symptoms, the presence of which would allow the most likely diagnosis. In the last decade, a triad of signs has been proposed - tachycardia, sweating and headache. Indeed, the detection of these symptoms was very specific for chromaffinoma - 92.8%, but the presence of all three signs in one patient is found only in 6.6% of cases. The greatest probability of a fechromocytoma exists in thin or thin patients with cold extremities and purplish-red skin tone on the hands, forearms, feet, shins, in the knee joint area, with marked sweating and a crisis course of arterial hypertension, especially if they have short-term episodes rise in blood pressure above 200/100 mm Hg. St., accompanied by a sharp headache, severe pallor, sweating, tachycardia (rarely bradycardia), nausea and vomiting, weakness (symptoms are given in descending order).

At present, there is no doubt about the diagnostic value of the quantitative determination of catecholamines in blood and urine, but there is still a debate about what is most conclusive - the study of the precursors of catecholamines or the products of their metabolism. The most accurate method of diagnosis and differential diagnosis of chromaffinoma is the study of a 3-hour excretion of adrenaline (A), noradrenaline (HA) and their main metabolite, vanillylmandelic acid (CMC) after a spontaneous or provoked hypertonic crisis. Determining only the daily excretion of catecholamines and vanillylmandelic acid leads to false-negative conclusions in almost 25% of cases, which is one of the main sources of diagnostic errors.

It should be especially emphasized that the study of catecholamines should not be conducted against the background of patients receiving dopegit. As a rule, in such cases a significant (sometimes tens of times) increase in the level of excretion of catecholamines is detected, while the excretion of vanillylmandelic acid remains within the normal range.

With prolonged treatment with dopegit, especially in large doses, increased excretion of epinephrine and norepinephrine may remain for a month or more. 3-5 days before the study, patients are not recommended the use of citrus fruits, bananas, products containing vanillin (chocolate and some confectionery), it is not desirable to take analgin or other drugs that it includes. With the fluorometric method of determining vanillylmandelic acid analgin significantly distorts the results of the study in the direction of false positive diagnosis.

Pharmacological tests for diagnosis and differential diagnosis of pheochromocytomas are based either on the ability of drugs to stimulate tumor secretion of catecholamines, or to block the peripheral vasopressor effect of the latter. The danger of carrying out the tests is the unpredictability of the magnitude of the hyper- or hypotensive reaction. In the literature of previous years, there are reports of severe consequences of pharmacological tests, and sometimes - lethal outcomes. Conducting provocative samples with suspicion of chromaffin is indicated in patients with any form of hypertension with an initial systolic blood pressure not exceeding 150 mm Hg. Art. And normal or slightly elevated daily excretion of catecholamines and vanillylmandelic acid. The sample, for example, with histamine is carried out by rapid intravenous injection of 0.1-0.2 ml of a 0.1% solution in 2 ml of physiological sodium chloride solution. Arterial pressure is measured every 30 seconds in the first 5 minutes and a minute later for the next 5 minutes. As a rule, at the 30th second after the administration of histamine, there is a decrease from the initial systolic and diastolic arterial pressure by 5-15 mm Hg. Art. The greatest rise in blood pressure is observed between 60 and 120 seconds. In patients with a tumor of chromaffin tissue, the rise in systolic blood pressure is (82 ± 14) mm Hg. St, and diastolic - (51 + 14) mm Hg. , whereas in patients with hypertension of a different etiology this value does not exceed, respectively, (31 ± 12) and (20 ± 10) mm Hg. Art. Given the possibility of a pronounced hypertensive reaction during a provocative test, preparations of alpha-blocking action should always be ready. A mandatory condition for carrying out the tests is to study the 3-hour excretion of catecholamines and vanillylmandelic acid after them, regardless of the nature of the change in blood pressure during the test.

In addition to histamine, such drugs as tyramine and glucagon have a similar stimulating property, however, unlike histamine, the latter does not cause vegetative reactions in the form of hot flashes and sweating, so it is much easier to tolerate.

The most common pharmacological samples that block the peripheral vasopressor effect of catecholamines include tests with regimen and tropafen. Intravenous injection of 10-20 mg of tropaphene into a patient with chromaffinoma at the time of an attack lowers blood pressure for at least 2-3 minutes by at least 68/40 mm Hg. St., while in patients with hypertension of other genesis - no more than 60/37 mm Hg. Therefore, in addition to the diagnostic value, tropaphene is used in the symptomatic treatment of catecholamine crises due to the tumor process.

Topical diagnosis of pheochromocytoma. The presence of the catecholamine-producing neoplasm, proved by the results of clinical and laboratory studies, is the basis for the next stage of diagnostics - detection of the location of the tumor or tumors, considering that in 10% of cases it is possible to have bilateral or adenocarpal localization of chromaffinoma. For topical diagnosis, the most difficult cases are the cases of the adrenal gland neoplasm. It is known that in 96% of the chromaffinoma is localized within the abdominal cavity and retroperitoneal space: from the diaphragm to the small pelvis (adrenal glands, para-aortic, Zuckerkandl organ, aortic bifurcation, bladder, uterine ligament, ovaries). In the remaining 4% of cases, chromaffinomas can be located in the thoracic cavity, neck area, pericardium, skull, spinal canal.

Palpation of the abdominal cavity under the control of arterial pressure for the purpose of localization of the ferhomocytoma has long been left as the most inaccurate and dangerous method of diagnosis.

Ordinary radiography or fluoroscopy of the thoracic organs in a straight line, and if necessary in the lateral and oblique projections allows to identify or exclude the intrathoracic location of the fehromocytoma.

Among the invasive methods, the tomography of the adrenal glands has recently been widely used against the backdrop of a gas (oxygen, nitrous oxide, carbon dioxide) that is preset in the retroperitoneal space. At present, it has almost lost its importance mainly because of its traumatic nature, and also as a result of the introduction of more advanced and safe methods of research into clinical practice. Another disadvantage of retro-pneumoperitonography is the limited nature of the establishment of a metastatic process and the detection of neoplasms of adrenal-adrenal localization. An essential addition to this method is excretory urography, which allows to differentiate the shadow of the kidney from the shadow of the tumor, and also to detect the chromaffinic organ of Zuckerkandl by the characteristic deviation of the left ureter.

Arteriographic methods (aortography, selective arteriography of renal and possibly adrenal arteries) have not been widely used because of low vascularization of most tumors.

Catheterization of veins is mainly used to determine in blood samples in various ways of its outflow along the course of the lower and upper hollow veins levels of catecholamines, the maximum content of which in the blood can be indirectly judged about the approximate localization of the functioning neoplasm. As for the retrograde adrenal venography, it can be performed, as a rule, on the left and with great difficulty to the right, besides the retrograde injection of a contrast agent into the tumor can lead to a severe hypertensive crisis during the study.

Among the non-invasive methods of topical diagnosis of the fechromocytoma, echography and computed tomography have become the most widely recognized . The parallel use of these methods makes it possible to determine the localization, size, prevalence and malignancy (metastasis) of the tumor process in almost all patients before surgery. Some difficulties arise in echography in patients with relapse of the fechromocytoma and in neoplasms up to 2 cm in diameter, located in the left adrenal gland, with errors mostly false positive.

Recently, among the radiological methods of studying the adrenal glands (cholesterol, gallium), gamma-matography with the help of methylbenzylguanidine is widely introduced into everyday practice. The latter, as shown by numerous studies, is a substance tropic to chromaffin tissue, which allows, along with tumors of the adrenal glands, to isolate neoplasms of adrenal glandular localization, as well as distant metastases.

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