Diagnosis of tuberculosis of intrathoracic lymph nodes

Differential diagnostics

Tuberculosis of the intrathoracic lymph nodes must be differentiated from pathological changes in the mediastinum and lung root of non-tuberculous etiology. More than 30 diseases of this area detected by X-ray examination have been described. In general, they can be divided into three main groups:

• tumor-like lesions of the mediastinal organs;
• non-specific adenopathy;
• anomalies in the development of blood vessels of the chest organs.

When conducting differential diagnostics, the X-ray anatomical structure of the mediastinum should be taken into account. Being part of the thoracic cavity, the mediastinum is limited in front by the posterior wall of the sternum and costal cartilages, behind by the spinal column, on the sides by the medial pleural layers, below by the diaphragm, and above by the thoracic aperture.

Children with diseases of the anterior and posterior mediastinum are referred for examination to tuberculosis institutions due to suspected specific process in the intrathoracic lymph nodes. Usually these are children who have been in contact with a patient with active tuberculosis or with changes in sensitivity to tuberculin. Virage, hyperergic tuberculin reactions, an increase in the papule size by more than 6 mm according to the Mantoux test with 2 TE indicate infection. In such cases, the radiologically documented expansion of the mediastinal shadow is interpreted unambiguously - suspected tuberculosis of the intrathoracic lymph nodes. Localization of the formation in the anterior or posterior mediastinum allows us to exclude a specific process in the intrathoracic lymph nodes, which are typically located in the central mediastinum.

The following can be attributed to the volumetric formations affecting the organs of the mediastinum and causing difficulties in differential diagnostics with tuberculous bronchitis in children: hyperplasia of the thymus gland, thymomas, dermoid cysts and teratomas, neurogenic formations, lymphogranulomatosis, lymphocytic leukemia, sarcoma and sarcoidosis. Most often, it is necessary to distinguish tuberculosis of the intrathoracic lymph nodes from mediastinal forms of systemic lesions, benign and malignant lymphomas (thoracic sarcoidosis, lymphogranulomatosis, lymphocytic leukemia, lymphosarcoma), inflammatory nonspecific adenopathy (reactive and viral).

Thymus hyperplasia, thymomas. Thymus hyperplasia occurs in infancy and early childhood. The term "thymoma" covers all types of tumors and cysts of the thymus gland. In a significant number of cases, thymus lesions are asymptomatic. As the tumor process develops, clinical manifestations occur - symptoms of pressure on adjacent organs, as well as symptoms of hormonal activity. Radiographically, thymoma is displayed as an expansion of the mediastinum on one or both sides. More often, it is located asymmetrically. The favorite localization is the upper and middle sections of the anterior mediastinum. On the radiograph, thymoma, as a rule, can be traced from the level of the clavicle, fills the retrosternal space and, narrowing downwards, depending on the size, can extend to the diaphragm. The shadow is uniform, has a sharp contour, slightly convex towards the lung tissue. When the enlarged lobes are displaced to one side, the widened mediastinum has a bicyclic character. The size and shape of the tumor-transformed lobes of the thymus gland vary widely. The literature indicates possible waviness of the contours and a pear-shaped form, as well as inclusions of calcium salts. This creates a similarity with hyperplasia of the intrathoracic lymph nodes. Topical diagnostics is of decisive importance in differentiation.

Dermoid cysts and teratomas are also localized in the anterior mediastinum. Dermoid cysts are defects of embryonic development - derivatives of the ectoderm. Accordingly, such elements as skin, hair, sweat and sebaceous glands are found in them. Elements of all three germ layers - ecto-, meso- and endoderm (skin with its appendages, muscles, nervous and bone tissue and even elements of individual organs - teeth, jaws, etc.) are found in teratomas. Dermoid cysts and teratomas, as a rule, do not manifest themselves clinically, they are usually identified by X-ray examination. The typical localization of teratomas is the middle section of the anterior mediastinum. Dermoid cysts are characterized by very slow growth. The decisive factor in diagnostics is the display of bone tissue inclusions (for example, teeth, jaw fragments, phalanges). In the absence of documented inclusions, the X-ray picture corresponds to a benign tumor.

Neurogenic tumors are the most common tumors and cysts of the mediastinum. They occur at all ages, including newborns. Most often, these are neurinomas - benign tumors that develop from Schwann cells. Malignant neurinomas develop rarely. Clinical symptoms of neurinomas are uncharacteristic, the course is long, asymptomatic. They are most often detected during preventive X-ray examination. X-ray:

• On a direct radiograph, a tumor is detected paravertebrally in the costovertebral angle, which, as a rule, has the shape of an elongated semi-oval, with a wide base adjacent to the spine:
• On the lateral image, the shadow of the tumor also has a wide base adjacent to the spine, and its convexity faces forward.

The growth rate of neurinomas may also vary. The structure of the shadow is uniform, the contours are clear, sometimes vaguely bumpy. Neurinomas do not pulsate and do not move when the position of the body of the examined person changes.

Sarcoidosis. Tuberculosis of the intrathoracic lymph nodes is differentiated from stage I sarcoidosis. According to modern concepts, sarcoidosis is a chronic disease of unclear etiology, characterized by damage to the lymphatic system, internal organs and skin with the formation of specific granulomas surrounded by a layer of hyalinosis. Intrathoracic lymph nodes are affected in 100% of cases, while other organs are affected less often. Sarcoidosis occurs in older children and adolescents. Clinical manifestations of sarcoidosis are varied. In most cases, the disease is asymptomatic and is detected by chance - during fluorographic examination. In 20% of cases, an acute onset is possible, accompanied by Löfgren's syndrome (an increase in body temperature to 38-39 ° C, erythema nodosum, joint pain and intrathoracic adenopathy). Some patients have a subacute onset with a rise in body temperature to subfebrile levels, dry cough, general weakness, and joint pain. A number of signs distinguish tuberculosis of the intrathoracic lymph nodes from sarcoidosis. Sarcoidosis is characterized by tuberculin anergy - in 85-90% of cases, tuberculin reactions are negative, while in tuberculous bronchoadenitis they are positive. In more than half of cases, sarcoidosis is latent, without pronounced clinical manifestations. In the hemogram of sarcoidosis, leukopenia and lymphopenia, monocytosis, eosinophilia with a normal or slightly increased ESR are sometimes noted. In the blood serum - an increase in the content of gamma globulins, and the concentration of calcium in the blood and urine also increases. The radiographic picture of sarcoidosis of the intrathoracic lymph nodes is characterized, with rare exceptions, by their bilateral symmetrical enlargement and sharp delimitation. The degree of enlargement is significant, like adenomegaly. The structural abnormalities are of the same nature, and there are no changes in the pulmonary pattern around the roots. In case of significant diagnostic difficulties, a biopsy is indicated, if possible, of the peripheral lymph nodes; if they are absent, mediastinoscopy with biopsy is performed. Histological examination of sarcoid granulomas is characterized by monomorphism, they have the same size, shape, and structure. Granulomas consist of epithelioid cells. Unlike tuberculosis, the centers of granulomas do not have necrosis. In rare cases, giant cells of the Pirogov-Langhans cell type may be encountered. Granulomas are delimited from the surrounding tissue by a border of reticular fibers and hyaline. The leukocyte shaft typical of tuberculosis is absent.

Lymphogranulomatosis. Clinical and radiological manifestations of tuberculosis of the intrathoracic lymph nodes are similar to lymphogranulomatosis. Symptoms such as weight loss, weakness, increases in body temperature to subfebrile and febrile numbers, radiographically determined enlarged intrathoracic lymph nodes, are found in both diseases. In lymphogranulomatosis, due to the development of the immunological deficiency syndrome, tuberculin reactions are negative even in cases where the disease was preceded by positive sensitivity to tuberculin. Peripheral lymph nodes in lymphogranulomatosis are affected in 90-95% of cases and are determined mainly in the cervical and supraclavicular regions. Unlike tuberculosis, they can reach significant sizes, have a woody density, are not fused with the surrounding tissue, and are usually not subject to purulent melting. Lymphogranulomatosis is characterized by anemia, leukocytosis with neutrophilia and progressive lymphopenia, eosinophilia. Tuberculosis is not characterized by changes in red blood, leukocytosis is less pronounced, lymphocytosis is possible. X-ray examination of lymphogranulomatosis reveals tumor-like lymph node hyperplasia, the degree of their increase is significant. The process, as a rule, has a symmetrical distribution. The structure of tumor-transformed lymph nodes is uniform. The upper mediastinum appears expanded, with clear polycyclic outlines.

Bronchological examination usually reveals indirect signs of enlarged intrathoracic lymph nodes, while tuberculous bronchoadenitis may show specific pathology in the bronchi and limited catarrhal endobronchitis. Microscopic examination reveals polymorphic cellular composition in favor of lymphogranulomatosis: neutrophils, lymphocytes, plasma and reticuloendothelial cells, and a fairly high percentage of eosinophils are determined. The presence of Berezovsky-Sternberg cells verifies the diagnosis.

Lymphocytic leukemia. Sarcoma. Enlargement of intrathoracic lymph nodes in lymphocytic leukemia and sarcoma can also simulate the picture of tuberculous bronchoadenitis. Unlike tuberculosis, tuberculin reactions are negative. The leukogram is of great importance. Leukemia is characterized by a sharp increase in the number of lymphocytes; in addition to normal lymphocytes, their young and pathological forms, blast cells are determined in the smear. The diagnosis is clarified by sternal puncture and examination of bone marrow obtained by trepanobiopsy. The lymph nodes are enlarged according to the tumor type. The development of lymphocytic leukemia in childhood and adolescence leads, as a rule, to the involvement of all groups of intrathoracic lymph nodes in the process, forming large symmetrical conglomerates of a homogeneous structure with clear polycyclic contours. Rapid progression of the disease can cause compression syndrome with impaired bronchial patency and compression of the superior vena cava. Hematological examination - myelogram, trepanobiopsy - is of decisive importance in diagnostics. The distinctive recognition of sarcoma from tuberculosis is helped by the sign of symmetrical damage, a significant increase in intrathoracic lymph nodes with a uniform structure and rapid growth, which is especially characteristic of children and adolescents.

Non-specific adenopathy. In some cases, tuberculosis of the intrathoracic lymph nodes should be differentiated from non-specific diseases accompanied by intrathoracic adenopathy syndrome: measles, whooping cough, viral infections. The need for differential diagnostics most often arises in a child infected with MBT. Children with non-specific adenopathy in the anamnesis usually have frequent acute respiratory viral infections, diseases of the ENT organs. In the clinical status of the child, changes in reactivity are noted, occurring as allergic syndromes or diathesis. X-ray examination establishes the degree of enlargement of the intrathoracic nodes is greater than is typical for tuberculosis. The structure of the lymph nodes is homogeneous. In the acute period, a diffuse increase in the pulmonary pattern is noted, caused by hyperemia, interstitial edema. Dynamic observation indicates involution of the process in a relatively short time. Diagnostic tracheobronchoscopy in patients with non-specific intrathoracic adenopathy usually reveals a bronchological picture of diffuse non-specific endobronchitis. Specific adenopathy is complicated by limited processes in the bronchi - tuberculosis at different stages of its development or catarrhal endobronchitis. As a rule, such children often consult a doctor with complaints identical to tuberculosis intoxication (long-term subfebrile condition), frequent acute respiratory infections, dry cough, poor appetite, drowsiness, etc.

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