What Is the Cause of Sarcoidosis?

Sarcoidosis is a non-caseous necrotizing epithelial cell granulomatous inflammatory disease with an unknown cause. It mainly invades the lung parenchyma and involves multiple organs throughout the body, such as lymph nodes, skin, joints, liver, kidneys, and heart After a relatively insidious clinical attack, patients may die suddenly due to complete atrioventricular block and / or congestive heart failure, and even sudden death is the first symptom.

Basic Information

English name

sarcoidosis

Visiting department

Respiratory Medicine

Common symptoms

Fever, anorexia, dry cough, wheezing, dyspnea, spots or pimples-like rash, and joint pain, etc.

Contagious

no

Causes of sarcoidosis

The cause is unknown.

Clinical manifestations of sarcoidosis

Sarcoidosis is a systemic disease. Except for the heart, other organs, especially the lungs, lymph nodes, and skin can be affected. May have fever, malaise, anorexia, weight loss, dry cough, wheezing, dyspnea, spots or pimples-like rash, and joint pain. In addition, the eyes are mostly uveal inflammation; those involving the conjunctiva, retina, and lacrimal glands can cause visual impairment. When patients with sarcoidosis have paratracheal lymphadenopathy with some acute peripheral arthritis, uveitis, and nodular erythema, they are called acute sarcoidosis or Laeffgren syndrome; and anterior uveitis with mumps People with facial paralysis are called Heerfordt syndrome.

Sarcoidosis test

Blood test

During the progress of the activity, there may be leukopenia, anemia, and increased erythrocyte sedimentation. In some patients, the serum globulin is partially increased, with IgG being more common, followed by IgG and IgM being less common. Plasma albumin decreases. Serum calcium increased, serum uric acid increased, and serum alkaline phosphatase increased. Serum angiotensin-converting enzyme (SACE) activity increases during the acute phase and is of reference significance for diagnosis. Serum interleukin-2 receptor (IL-2R) and soluble interleukin-2 receptor (sIL-2R) are elevated. The diagnosis of arthritis is of great significance. In some patients, the levels of a1-antitrypsin, lysozyme, ß2-microglobulin (ß2-MG), serum adenosine dehydrogenase (ADA), and fibronectin (Fn) are elevated, which has certain reference significance in clinical practice.

2. Tuberculin test

Some patients had no or very weak response to the 100U tuberculin skin test.

3. Sarcoidosis antigen test

The lymph nodes or spleen tissues of patients with acute nodules were used to make a 1:10 saline suspension as the antigen. Take 0.1 ~ 0.2ml of the suspension for intradermal injection. After 10 days, purple-red papules appear at the injection site. After 4 ~ 6 weeks, it spreads to 3 ~ 8mm, forming granulomas, which is a positive reaction. The tissues with positive reaction were removed for tissue diagnosis, and the positive rate was about 75% to 85%. There were 2% to 5% false positive reactions. Because there is no standard antigen, the application is limited, and it has been gradually eliminated in recent years.

4. Biopsy

Pathological examination of skin lesions, lymph nodes, anterior oblique fat pads, muscles and other tissues can help diagnosis. Extracting multiple tissue biopsies at different locations can improve the diagnostic positive rate.

5. Bronchoalveolar lavage fluid examination (BALF)

In BALF examination of patients with sarcoidosis, the lymphocyte and multinuclear leukocyte counts increased significantly during the alveolitis stage, mainly due to the increase of T lymphocytes, and the CD4 ⁺ , CD4 ⁺ / CD8 ⁺ ratios increased significantly. In addition, the function of B cells is also significantly enhanced. In BALF, IgG and IgA increased, especially IgG1 and IgG3 increased.

6. Transbronchial lung biopsy (TBLB)

The TBLB positive rate of sarcoidosis can reach 63% to 97%, the positive rate of stage 0 is very low, positive rate can be obtained in more than 50% of stage , and the positive rate of stage and is higher.

7. X-ray inspection

Abnormal chest X-ray findings are often the first finding of sarcoidosis, and most patients are accompanied by changes in chest radiographs.

8. Chest Computer Tomography (CT)

The accuracy of ordinary X-ray chest radiographs for sarcoidosis is only 50%, and even a few people with normal chest radiographs have sarcoidosis. Therefore, CT has been widely used in the diagnosis of sarcoidosis in recent years. Can accurately estimate the type of sarcoidosis, the degree of pulmonary interstitial lesions and the status of lymphadenopathy. In particular, high-resolution thin-layer CT is more accurate for the diagnosis of pulmonary interstitial lesions, and its layer thickness is 1 to 2 mm.

9. ⁶⁷ gallium ( ⁶⁷ Ga) lung scan

Granuloma-active macrophage uptake of ⁶⁷ Ga was significantly increased. Granulomatous lesions and hilar lymph nodes in pulmonary sarcoidosis can be shown by ⁶⁷ Ga, which can assist diagnosis, but is not specific.

Sarcoidosis diagnosis

The diagnosis of sarcoidosis is based on clinical signs and symptoms and tissue biopsy, and excludes other granulomatous diseases. The diagnostic criteria can be summarized as follows: chest imaging shows symmetrical enlargement of bilateral hilar and mediastinal lymph nodes with or without intra-pulmonary grids, nodular or sheet shadows; non-cheese confirmed by histological biopsy Necrotizing granulomatosis, and negative acid staining; increased SACE or SL activity; high sIL-2R in serum or BALF; old tuberculin (OT) or PPD test negative or weakly positive; lymphocytes in BALF> 10 %, And the ratio of CD4 ⁺ / CD8 ⁺ 3; hypercalcemia, hyperuricemia; Kveim test positive; except for tuberculosis or other granulomatous diseases. Among the above nine clauses, , , are the main conditions, and others are secondary conditions.

Differential diagnosis of sarcoidosis

Hilar lymph node tuberculosis

Patients are younger, mostly under 20 years of age, often have low-level symptoms of toxicity, tuberculin tests are mostly positive, hilar lymphadenopathy is generally unilateral, and sometimes calcified. Visible lung primary lesions.

Lymphoma

Common systemic symptoms include fever, weight loss, anemia, etc., pleural involvement, pleural effusion, and intrathoracic lymphadenopathy are mostly unilateral or bilateral asymmetric enlargement, often involving the upper mediastinum, subbulge, and mediastinal lymph nodes. Mediastinal compression can cause superior vena cava obstruction syndrome. Combination with other examinations and biopsy can be used for identification.

3. hilar metastatic tumor

Lung cancer and extrapulmonary cancers have metastasized to hilar lymph nodes and have corresponding symptoms and signs. Further examination of suspicious primary lesions can help identify them.

4. Other granulomatous diseases

Such as exogenous alveolitis, beryllium disease, silicosis, infectious, chemical factors caused by granulomas, should be distinguished from sarcoidosis, combined with clinical data and related examinations and comprehensive analysis and judgment.

Sarcoidosis Treatment

Because most patients can resolve on their own, stable and asymptomatic patients do not require treatment. Patients with obvious symptoms of stage and and extrathoracic sarcoidosis such as ocular sarcoidosis, invasion of sarcoidosis in the nervous system, skin and myocardial involvement, continuous increase in blood calcium, urine calcium, and significantly increased SACE levels treatment. Prednisone is commonly used, gradually reduced after 4 weeks, and maintained for one year or longer. Long-term use of glucocorticoids should closely observe the side effects of hormones, followed by chloroquine, methotrexate, azathioprine, cyclophosphamide and other treatments.

Any drug that can cause an increase in blood calcium and urine calcium, such as vitamin D, is contraindicated.

Sarcoidosis prognosis

Related to sarcoidosis. Acute onset patients have a better prognosis after treatment or spontaneous remission; chronic progression, invasion of multiple organs, causing functional impairment, extensive fibrosis of the lung, or acute infection have a poor prognosis. The cause of death is often caused by pulmonary heart disease or myocardial and brain invasion.