Microscopic polyangiitis

Introduction to microvascular inflammation under the microscope Microscopic polyangiitis (MPA) is a systemic necrotizing vasculitis that mainly affects small blood vessels. It can invade small arteries, arterioles, capillaries and venules of organs such as kidneys, skin and lungs. Often manifested as necrotizing glomerulonephritis and pulmonary capillary vasculitis. In 1948, Davson et al first proposed a subtype characterized by segmental necrotizing glomerulonephritis in nodular polyarteritis. It is microscopic polyarteritis under the microscope, because it mainly involves small blood vessels including veins, so it is often called microscopic polyangiitis. basic knowledge The proportion of illness: 0.005% Susceptible people: no specific population Mode of infection: non-infectious Complications: orchitis, arthritis

Microscopic causes of polyangiitis

Anti-neutrophil cytoplasmic antibodies (30%):

Anti-neutrophil cytoplasmic antibodies are present in many microscopic polyangiitis sera. Microscopic polyangiitis, like Wegener's granulomatosis, is a vasculitis without immune complex deposition, so antigen-antibody immune complexes Mediated vascular injury is of little significance in the pathogenesis of microvascular polyangiitis. It is currently believed that anti-neutrophil cytoplasmic antibodies may play a role in mediating neutrophil activation: infection and other factors Microscopically, the levels of various inflammatory cytokines such as tumor necrosis factor- and interleukin-1 in the serum of patients with polyangiitis are elevated, and they induce the expression of adhesion molecules, which makes polymorphonuclear leukocytes easily adhere to the vascular endothelium. It also induces the transfer of protease-3 from polymorphonuclear leukocytes from the cytoplasmic azurophilic granules to the cell surface. When anti-neutrophil cytoplasmic antibodies bind to protease-3 on the leukocyte surface, they activate leukocytes, causing Degranulation of polymorphonuclear leukocytes releases reactive oxygen species and lysosomal enzymes, leading to peripheral vascular injury and necrosis. On the other hand, cells such as tumor necrosis factor- The factor also activates vascular endothelial cells, and the activated endothelial cells express antigens such as myeloperoxidase and protease-3, so that anti-neutrophil cytoplasmic antibodies directly bind to endothelial cells through their specific antigens, and are mediated by antibodies. The cytotoxic killing pathway dissolves the vascular endothelium and causes damage to blood vessels.

Anti-endothelial cell antibody (20%):

Anti-endothelial cell antibodies are present in many systemic vasculitis, including microscopic polyangiitis, but the role of anti-endothelial cell antibodies in microscopic polyangiitis is not well understood. Studies have found that many anti-endothelial cell antibodies are not pathogenic. Sexual, anti-endothelial cell antibodies cause endothelial cell damage, the mechanism of which may be achieved by complement-mediated lysis pathways and antibody-mediated cytotoxicity.

Microscopic polyangiitis prevention

How to prevent polyangiitis under the microscope?

Primary prevention

(1) to prevent possible incentives, the room should not be too cold and humid, the temperature should be appropriate.

(2) Prevent infection, strengthen exercise, enhance physical fitness, improve autoimmune function, and regular life.

(3) Strengthen nutrition, not cold drink and over-flavored food, avoid spicy food and avoid alcohol and tobacco.

2. Secondary prevention

(1) Early diagnosis is difficult. Any young person, especially a woman, should consider the disease, systemic fever, joint or myalgia, ischemic symptoms of unilateral or bilateral limbs, and head ischemia. Symptoms, refractory hypertension symptoms, vascular murmur embolism, should be diagnosed as soon as possible.

(2) Comprehensive treatment to reduce complications and improve prognosis.

1 medical treatment: including control of infection, glucocorticoids, improvement of microcirculation, anticoagulation, antihypertensive drugs and TCM syndrome differentiation treatment.

2 surgical treatment: percutaneous transluminal angioplasty, arterial bypass, valve repair and nephrectomy.

3. Three levels of prevention

At present, there is no specific drug for the treatment of aortitis. Traditional Chinese medicine has the functions of regulating immunity, clearing away heat and detoxifying, promoting blood circulation and removing blood stasis. In addition, it is necessary to strengthen systemic nutrition, physical exercise, regular life, work and rest, and comfortable mood.

Microscopic polyangiitis complications Complications orchitis

Usually complicated by orchitis and arthritis.

Microscopic symptoms of multi-vessel inflammation Common symptoms Pinocide rash chest pain hematuria proteinuria limb ischemic skin necrosis weight loss reticular leucorrhea voice abdominal pain

Microscopic polyangiitis has a mixed onset, MPA can be acute onset of acute glomerulonephritis, pulmonary hemorrhage and hemoptysis, and some can also be very concealed for several years, with intermittent purpura, mild kidney damage Intermittent hemoptysis, etc., typical cases have clinical manifestations of skin-lung-kidney.

Systemic symptoms

Microscopic polyangiitis patients are often accompanied by general general conditions, including fever, fatigue, anorexia, joint pain and weight loss.

2. Skin performance

MPA can have a variety of rashes, with purpura and hyperemic rash on the skin. The rash can appear alone or at the same time as other clinical symptoms. The pathology is mostly white blood cell vasculitis, except for rash. Patients with MPA may also have reticular leukoplakia, skin ulcers, skin necrosis, gangrene and limb ischemia, necrotic nodules, urticaria and vasculitis-related urticaria often lasting for more than 24 hours.

3. Kidney damage

Renal damage is the most common clinical manifestation of MPA. The lesions vary widely. Very few patients may have no renal disease. Most patients have proteinuria, hematuria, various casts, edema and renal hypertension. Some patients have renal function. Incomplete, progressive deterioration can lead to renal failure, and 25% to 45% of patients eventually require hemodialysis.

The renal pathology of MPA is necrotizing glomerulonephritis, characterized by segmental necrosis with crescent formation, little or no capillary endothelial cell proliferation, glomerular histology with little or no immune complex deposition, electron microscopy Little or no electron dense deposits, these characteristics are different from other immune complex-mediated glomerulonephritis and anti-glomerular basement membrane antibody-mediated Goodpasture syndrome, but with Wegener's granulomatous kidney Lesions and idiopathic progressive glomerulonephritis are sometimes difficult to identify and pathological changes under MPA light microscopy.

4. Lung damage

About half of MPA patients have alveolar capillary vasculitis due to lung damage, 12% to 29% of patients have diffuse alveolar hemorrhage, respiratory distress syndrome can be seen, lungs can be heard and voice, due to diffuse pulmonary interstitial Changes and lung infiltration of inflammatory cells, about one-third of patients with cough, hemoptysis, anemia, a large number of pulmonary hemorrhage can lead to breathing difficulties, and even death, some patients can appear on the basis of diffuse alveolar hemorrhage Fibrosis.

5. The nervous system

20% to 30% of patients with MPA have symptoms of neurological damage, of which about 57% have multiple mononeuritis or polyneuropathy, and about 11% of patients may have central nervous system involvement, often manifested as seizures.

6. Digestive system

The digestive tract can also be involved, manifested as gastrointestinal bleeding, pancreatitis and abdominal pain caused by intestinal ischemia. In severe cases, ischemia can occur due to small vasculitis and thrombosis of the gastrointestinal tract, leading to intestinal perforation.

7. Cardiovascular system

MPA can also affect the cardiovascular system, patients can have chest pain and heart failure symptoms, clinically seen hypertension, myocardial infarction and pericarditis.

8. Other

Some patients also have otolaryngology, such as sinusitis, which is more likely to be confused with Wegener's granulomatosis. A small number of patients may also have arthritis, joint pain and testicular pain caused by orchitis.

Ocular symptoms include redness and pain in the eyes and decreased vision, and ophthalmologic examinations include retinal hemorrhage, scleritis, and uveitis.

There is no uniform standard for the diagnosis of this disease. If there is systemic damage and lung involvement, kidney involvement and high purplish purpura should consider the diagnosis of MPA, especially those with p-ANCA positive, renal biopsy and skin or Other visceral biopsy is beneficial for the diagnosis of MPA, and some patients need to exclude infective endocarditis.

Microscopic examination of polyangiitis

What are the tests for polyangiitis under the microscope?

1. routine inspection

In MPA, indicators of acute phase inflammation such as ESR, elevated CRP, some patients with anemia, white blood cells and thrombocytosis, proteinuria in the kidney, microscopic hematuria and red blood cell cast, elevated serum creatinine and urea nitrogen levels .

2. Immunological examination

C3 and C4 levels are normal, about 80% of MPA patients are positive for anti-neutrophil cytoplasmic antibodies (ANCA), which is an important diagnostic basis for MPA, of which about 60% of MPO-ANCA (p-ANCA) is positive, and lung involvement is Often this antibody, about 40% of patients are positive for PR3-ANCA (c-ANCA), about 40% of patients can find anti-cardiolipin antibodies (ACL), a small number of patients ANA, RF positive, Peking Union Medical College Hospital Of the 16 MPA patients diagnosed between 1995 and 2001, 13 (81.2%) were positive for ANCA, 11 (84.6%) were positive for P-ANCA, and 3 (23.1%) were positive for c-ANCA. One patient (7.7%) was positive for p-ANCA at the same time.

Chest X-ray: In the early stage, there are no characteristic bilateral nodular flaky shadows or vesicular infiltrates. Lung cavity is rare, and diffuse pulmonary parenchymal infiltrates secondary to alveolar capillary vasculitis and pulmonary hemorrhage can be seen. Pulmonary interstitial fibrosis can occur in the middle and late stages.

Diagnosis and identification of polyangiitis under microscope

What diseases are easily confused with polyangiitis under the microscope?

Before the diagnosis is confirmed, it needs to be differentiated from nodular polyarteritis and Wegener's granulomatosis.

1. Nodular polyarteritis (PAN) In the past, MPA was a type of PAN. As the disease became more and more in-depth, it was found that the clinical manifestations of the two were not identical. Therefore, the 1993 Church Hill Conference on vasculitis ( Chapel Hill consensus conference) lists MPA as a disease alone. According to the new definition, PAN is a necrotic inflammation involving the middle arteries and small arteries, without glomerulonephritis or microarteries, capillary or microvessel inflammation; MPA is a necrotizing vasculitis mainly involving small blood vessels, with little or no immune complex deposition. Among them, necrotizing glomerulonephritis is common, and pulmonary capillary vasculitis often occurs.

2. Wegener's granuloma (WG) WG is a vasculitis of small arteries and venules. The above, lower respiratory tract and renal lesions are the main clinical features, c-ANCA is more common, biopsy pathology shows small vessel wall or There is neutrophil infiltration around and necrotizing granuloma formation, while MPA rarely affects the upper respiratory tract, mainly p-ANCA positive, generally no granuloma formation.

3. Pulmonary hemorrhagic-nephritis syndrome (Goodpasture syndrome) Goodpasture syndrome, also known as anti-GMB disease with pulmonary hemorrhage, is due to damage to the alveolar and glomerular basement membrane. Pathogenicity, including repeated diffuse pulmonary hemorrhage, glomerulonephritis and circulating anti-glomerular basement membrane antibody (anti-GBM) triad, clinical manifestations of repeated diffuse pulmonary hemorrhage, anemia and renal hemorrhage (hematuria), lung and Renal biopsy showed that IgG and C3 against the basement membrane antibody were continuously and linearly deposited along the alveolar wall and the capillary wall of the glomerulus. The detection of anti-basement membrane antibody in the blood circulation was an important basis for the diagnosis of this disease.

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