What Is Allergic Vasculitis?

Allergic vasculitis is one of the most common vasculitis. It has been known as leukocyte fragmenting vasculitis, necrotizing nodular dermatitis, hypersensitivity vasculitis, nodular dermal allergic rash, allergic arteritis and Allergic vasculitis and other clinical manifestations are often prominent in patients with obvious skin damage or other organ involvement. Histopathological examination revealed cellulosic necrosis of the small vessel wall, a large number of neutrophil infiltration and nuclear fragmentation around the blood vessel, and red blood cell overflow. With the exception of fulminant and severe internal organ damage, the prognosis is generally good and can be recovered within a few weeks.

Basic Information

nickname

Leukocyte fragmenting vasculitis, necrotic nodular dermatitis, hypersensitivity vasculitis, etc.

Visiting department

Allergy Department, Rheumatology and Immunology Department

Common causes

Penicillin, sulfa, pesticides, herbicides, etc.

Common symptoms

Erythema, purpura, wind mass, pimples, etc.

Causes of allergic vasculitis

The occurrence of this disease is mainly caused by exogenous antigens. These exogenous antigens include roughly three types.

Drug

Including penicillin and its derivatives, sulfa, aspirin, etc.

Chemical substance

Such as pesticides, herbicides, petroleum preparations.

3. In vitro protein

Snake venom serum and various desensitizers.

Of these three types of allergens, drugs are the most common.

Clinical manifestations of allergic vasculitis

The onset of allergic vasculitis can be urgent and slow. The common symptoms in the whole body include fever, fatigue, fatigue, etc. The local manifestations are mainly skin symptoms, and a few patients have external skin involvement, such as joints, kidneys, lungs, digestive system, etc. .

Skin manifestation

The skin lesions are mostly symmetrical, often distributed in the lower limbs and buttocks, and can also occur in the upper limbs and chest and back. The skin lesions have polymorphic changes, mainly erythema, purpura, wind mass, pimples, blood blister, nodules and necrotic ulcers Chronic patients may occasionally have reticular plaques. The rash usually starts with millet to mung bean red papules and purpura, and develops into palpable purpura soon, protruding slightly from the skin surface, which can be felt by hand, and the finger pressure does not fade. Easy to distinguish from non-inflammatory purpura. The rash can range from the tip of the needle to the size of the broad bean. Small rashes are usually asymptomatic, and large rashes or fused skin rashes can be painful. The onset of the rash is irregular, which subsides for 1 to 4 weeks, and pigment spots can remain. Some patients had severe skin lesions, necrosis of the epidermis, formation of ulcers, scabs, and atrophic scars left after healing.

2. Outer skin manifestations

There may be joint pain when joints are involved, but generally there is no redness and fever. When the lung is violated, the patient has shortness of breath, hemoptysis, and pleural effusion. Abdominal pain, nausea, and upper gastrointestinal bleeding suggest gastrointestinal involvement. Central nervous system diseases include headache and diplopia. Heart involvement is rare and manifests as arrhythmia, which can cause heart failure in severe cases. When the kidney is damaged, edema, hematuria, etc. can be seen.

Allergic vasculitis test

Laboratory inspection

(1) Eosinophils often increase in blood tests , white blood cell counts can increase, erythrocyte sedimentation rate can increase, hyperglobulinemia and ADP and prostaglandin can be increased, generally no anemia, normal platelet count, time to coagulation normal. With IgG-IgM cryoglobulinemia, laboratory tests showed hypergammaemia and hypocomplementemia, and RF and HBsAg can be positive.

(2) Urine tests may include protein, red blood cells, white blood cells, and casts. In severe cases, proteinuria may occur in the area of nephrotic syndrome, and urea nitrogen and creatinine may be increased during renal dysfunction.

(3) Parasite eggs and red blood cells can be seen in some patients during routine examination of feces , and the occult blood test can be positive.

(4) Bone marrow looks like normal bone marrow.

(5) Positive capillary fragility test.

2. Auxiliary inspection

(1) Histopathological examination reveals diffuse small perivascular inflammation, and neutrophils accumulate around the blood vessels. Immunofluorescence examination showed that IgM and C3 were deposited on the vascular wall of the dermis. The main pathological feature of skin- allergic vasculitis is acute cellulosic necrosis, which starts in the vascular intima or subendothelial matrix, and then spreads to the entire vascular wall, with significant polymorphic cell response and eosinophil infiltration. The progression of lesions in vascular lesions is at the same stage, unlike in nodular polyarteritis. Examination showed that arteritis phlebitis and capillary vasodilatation under the dermal papilla to the reticular layer of the skin tissue showed vasodilatation of endothelial cells, edema of endothelial cells, thrombosis in the lumen, and fibrinoid degeneration or necrosis of the vessel wall. In the early stage of the disease, there were neutrophil-based cell infiltration around the blood vessels. Leukocyte fragmentation and nuclear dust and red blood cell extravasation were seen. In the later stage of the disease, mononuclear cell infiltration was predominant. Kidney changes Except for the skin, the kidney is the most affected part of the disease. The kidneys are normal or enlarged in size and have bleeding spots on the surface. Light microscopy showed that the smaller interlobular arteries, arterioles, veins, and capillaries had fibroid necrosis. The most prominent glomerular lesions were granulomatous lesions around the glomeruli. Cell proliferation in capillaries, and segmental or annular epithelial crescents and diffuse necrotizing glomerulonephritis can be seen. There are many types of kidney pathology in this disease, which are round cells with no or less immune complex crescentic nephritis. Infiltration and bleeding. Part of the tubules atrophied. Immunofluorescence showed a small amount of IgG, IgM and complement deposition or no immunoglobulin components in the mesangial area and capillary wall, but there was more fibrinogen precipitation in the renal capsule and glomerular necrotic vessel area. There were no obvious characteristic changes under the electron microscope, and there were no more electron dense materials.

The characteristic lesions of renal involvement in allergic vasculitis are necrotizing glomerulitis or focal necrotizing glomerulitis. Aggravated cases can be seen in diffuse necrotizing glomerulonephritis.

(2) X-ray examination may show focal or diffuse lung infiltration, or small nodules, with occasional pleural effusions when the lung is involved.

Diagnosis of allergic vasculitis

According to the above characteristics, the diagnosis of typical allergic vasculitis is not difficult. 1990 American Rheumatology Association (ARA) set a diagnostic standard for allergic vasculitis

1. Age of onset> 16 years.

2. Have a history of taking drugs before the illness.

3. Touchable purpura.

4. Macular pimple is one or more skin rashes of varying sizes that are flat and higher than the skin surface.

5. Skin venules or arterial sections show infiltration of neutrophils inside or outside blood vessels.

Those who meet 3 or more of the above 5 items can be diagnosed as allergic vasculitis. The standard sensitivity is 71% and the specificity is 93%.

Differential diagnosis of allergic vasculitis

Allergic purpura

Allergic purpura is more common in children, and skin lesions are manifested as subcutaneous bleeding maculopapular and maculopapular rash, without polymorphic skin lesions. Most people have a typical triad (purpura, joint pain, and abdominal pain), and more than half have hematuria, proteinuria, nephrotic syndrome, and even renal failure. Renal pathology suggests focal segmental sclerosing glomerulonephritis or diffuse mesangial proliferative glomerulonephritis, with a few severe cases manifesting as crescentic nephritis. Immunofluorescence showed IgA and complement glomerular mesangial area deposition, and its pathological changes were similar to those of primary IgA nephropathy. Whether the treatment of this disease is effective is very important to identify and remove the cause, especially the suspension of suspicious antigenic sensitization drugs has a key role in determining the prognosis. Other treatment principles are basically similar to nodular polyarteritis.

2. Thrombocytopenic purpura

Purpura skin lesions are large subcutaneous congestions and platelet counts are significantly reduced.

3. Polymorphic erythema

Skin lesions show edema erythema on the back of hands, feet, and back, dark red, and target-like appearance.

Allergic vasculitis treatment

Cause treatment

Quickly identify allergenic drugs or chemicals, warn patients to stop and guarantee that they will not be contacted in the future. Eliminate infection.

2. Drug treatment

(1) Glucocorticoids are effective for most patients, and the dosage of such drugs should be determined according to the severity of the disease. After the symptoms improve, the dose should be slowly reduced to the minimum maintenance amount or as directed by your doctor.

(2) If the patient's condition is relatively mild and only a small part of the skin is affected without internal organ damage, no special treatment is required, and treatment with this type of drug is sufficient.

(3) The mechanism of action of sulfone drugs is unknown, and may be related to the effects of stabilizing the lysosomal membrane. In some patients, only dapsone can effectively control the disease.

( 4) Immunosuppressive agents If patients have a poor response to glucocorticoids or are too intolerant due to glucocorticoid side effects, immunosuppressive treatment may be considered.

(5) Leukocyte function inhibitor

(6) Antibiotics The use of antibiotics is extremely necessary for patients with concurrent infections.

(7) Non-steroidal anti-inflammatory drugs are mainly symptomatic treatments, which have a significant effect on patients with fever and joint pain.