What Is Microscopic Polyangiitis?

In 1948, Davson et al. First proposed that there is a subtype characterized by segmental necrotizing glomerulonephritis in nodular polyarteritis, called microscopic polyarteritis (MPA), because it mainly involves Small blood vessels, including veins, are now mostly called microvasculitis under the microscope. In 1990, the American College of Rheumatology classification criteria for vasculitis did not list MPA separately. Therefore, under the previous microscope, polyangiitis was mostly attributed to nodular polyarteritis, and very few were attributed to Wegener's granulomatosis.

Basic Information

nickname

Polyarteritis under microscope

Visiting department

Vascular surgery

Common symptoms

Fever, fatigue, anorexia, joint pain and weight loss, skin ulcers, skin necrosis, gangrene, etc.

Causes of polyangiitis under the microscope

The cause of polyangiitis under the microscope is still unclear, and may be related to immune abnormalities in patients. It is also believed to be related to genetic and environmental factors and the pathogenesis of infection and disease.

Clinical manifestations of polyangiitis under a microscope

The onset of polyangiitis under the microscope varies rapidly. MPA can be acute onset of acute glomerulonephritis, pulmonary hemorrhage, and hemoptysis; some can also be very insidious, with years of onset, manifested by intermittent cyanosis, mild kidney damage, and intermittent hemoptysis. Typical cases have clinical manifestations of skin-lung-renal. Occurs during the winter, and most have pre-symptoms of upper respiratory infections or drug allergies. Non-specific symptoms include irregular fever, fatigue, rash, joint pain, myalgia, abdominal pain, neuritis, and weight loss.

Systemic symptoms

Patients with polyangiitis under the microscope are usually accompanied by general systemic conditions, including fever, fatigue, anorexia, joint pain, and weight loss.

2. Skin manifestations

MPA can appear various rashes, with cyanosis and congestive maculopapular rash above the skin. The rash can appear alone or concurrently with other clinical symptoms, and its pathology is mostly leukopenic vasculitis. In addition to rash, patients with MPA may also develop reticulated plaques, skin ulcers, skin necrosis, gangrene, and extremity ischemia, necrotic nodules, urticaria and urticaria-related urticaria, which usually last for more than 24 hours.

3. Kidney damage

Renal damage is the most common clinical manifestation of MPA, and the pathological changes are very different. Very few patients may have no renal disease. Most patients have proteinuria, hematuria, various casts, edema, and renal hypertension; some patients have progressive deterioration of renal insufficiency and renal failure. The renal pathology of MPA is necrotizing glomerulonephritis, which is characterized by segmental necrosis with crescent formation and little or no capillary endothelial cell proliferation. Glomerular histology and electron microscopy with little or no electron dense deposits.

4. Lung damage

About half of MPA patients have lung damage and alveolar capillaritis, and 12% to 29% of patients have diffuse alveolar hemorrhage. Examination revealed respiratory distress signs and snoring sounds in the lungs. Due to diffuse interstitial lung changes and lung infiltration of inflammatory cells, about one-third of patients develop cough, hemoptysis, and anemia, and a large amount of pulmonary bleeding can cause breathing difficulties and even death. Some patients may develop pulmonary fibrosis based on diffuse alveolar hemorrhage.

5. Nervous system

20% to 30% of MPA patients have symptoms of neurological damage, of which about 57% have polyneuritis 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 affected, manifesting as gastrointestinal bleeding, pancreatitis, and abdominal pain caused by intestinal ischemia. In severe cases, it can cause ischemia due to small vasculitis and thrombosis in the gastrointestinal tract, leading to perforation of the intestine.

7. Cardiovascular system

MPA can also affect the cardiovascular system. Patients may experience symptoms of chest pain and heart failure. Hypertension, myocardial infarction, and pericarditis can be seen clinically.

8. Other

Some patients also have ENT symptoms, such as sinusitis, which is more likely to be confused with Wegener's granulomatosis. A small number of patients may also have testicular pain due to arthritis, joint pain, and orchitis. There are also eye symptoms, including redness and pain in the eyes and decreased vision. Ophthalmic examination shows retinal hemorrhage, scleritis, and uveitis.

Polyangiitis examination under microscope

Routine inspection

In MPA, indicators that reflect acute inflammation (such as ESR, CRP) are elevated, and some patients have anemia, white blood cell counts, and thrombocytosis. Proteinuria, microscopic hematuria, and erythrocyte casts occur when the kidney is involved, and serum creatinine and urea nitrogen levels increase.

2. Immunological examination

C3 and C4 levels are normal or elevated. About 80% of MPA patients are positive for anti-neutrophil cytoplasmic antibody (ANCA), which is an important diagnostic basis for MPA. About 60% of them are positive for MPO-ANCA (p-ANCA). This antibody is often found in patients with lung involvement. Approximately 40% of patients are PR3-ANCA (c-ANCA) positive. Anticardiolipin antibodies can be found in about 40% of patients, and a small number of patients have positive antinuclear antibodies and rheumatoid factor.

3. Chest radiograph

Early, no characteristic bilateral irregular nodular patchy shadows or vesicle-like infiltrates can be found. Pulmonary cavities are rare. It can be seen that diffuse pulmonary parenchymal infiltrates secondary to alveolar capillary inflammation and pulmonary hemorrhage. Interstitial fibrosis occurs.

Diagnosis of polyangiitis under a microscope

There is no unified standard for polyangiitis under the microscope. The following conditions are helpful for the diagnosis of polyangiitis under the microscope:

1. Middle-aged and elderly, more common in men.

2. With prodromal symptoms of onset.

3. Renal damage manifestations: proteinuria, hematuria or (and) progressive progressive renal insufficiency.

4. Clinical manifestations with pulmonary or pulmonary-renal syndrome.

5. Accompanied by joints, eyes, ears, heart, gastrointestinal tract and other organs.

6. P-ANCA is positive.

7. Kidney and lung biopsy is helpful for diagnosis.

Polyangiitis treatment under the microscope

The treatment of this disease is mainly determined based on the extent of the disease, its progress, and the degree of inflammation.

The treatment of MPA can be divided into 3 stages. The first stage is to induce remission. The second stage is to maintain remission. This stage can be treated with moderate prednisone and maintained for cyclophosphamide for 12 months, or switched to azathioprine, Methotrexate and other maintenance remission; the third stage is to treat relapse, taking sulfa antibiotics has a certain effect on preventing relapse.

Patients with severe alveolar capillaritis with pulmonary hemorrhage should be treated in combination or with plasma exchange.