Small intestinal anaphylactoid purpura

Brief introduction of small intestinal allergic purpura Allergic purpura (also known as Henoeh-Sehönlein syndrome) is a clinically common allergic hemorrhagic disease with lesions mainly involving the capillary wall. Small intestinal allergic purpura is actually one of the clinical manifestations of allergic purpura in the gastrointestinal tract. basic knowledge The proportion of sickness: 0.01% Susceptible people: children Mode of infection: non-infectious Complications: Intussusception Intestinal obstruction

Small intestinal allergic purpura

(1) Causes of the disease

The disease is an immune disease, and its etiology has not yet been fully elucidated. The permeability and brittleness of the capillary wall may be increased due to the body's allergic reaction to certain allergic substances. The allergen may be caused by various factors, but The direct cause of the disease is often difficult to determine, and the factors related to the occurrence of this disease are:

1. Infection: including bacteria, viruses and parasites.

2. Drugs: penicillin, streptomycin, sulfonamides, isoniazid, sodium salicylate, quinine, etc.

3. Food: fish, shrimp, crab, egg, milk and other heterosexual proteins.

4. Others: such as cold, pollen inhalation or vaccination.

(two) pathogenesis

All kinds of allergens are prone to allergic reactions to a small number of people with allergies. The above factors cause autoimmune reactions, immune complexes damage small blood vessels, extensive capillary vasculitis, and even necrotizing arteritis. Permeability and fragility of the vessel wall lead to hemorrhage and edema of the subcutaneous tissue, mucosa and internal organs. Electron microscopy of the glomerular vascular membrane has immunological complex deposition. The immunofluorescence is mainly IgA (a small amount of IgG and IgM), C3 , fibrin / fibrinogen, so allergic purpura kidney damage is related to immune complexes.

Clinically, it is divided into two types: immediate (I type) allergy and immune complex (type III) allergy.

Allergic hypersensitivity (35%):

After receiving the allergen, the patient produces a large number of pro-cell IgE antibodies in the body, and the Fc segment can bind to the mast cells in the perivascular and connective tissues and the Fc receptor on the basophilic membrane in the blood. When exposed to allergens, the latter binds to the Fab segment of IgE that has been adsorbed on mast cells and basophilic granulocyte membranes, activates lipase in these cells, reduces intracellular cyclic adenosine monophosphate (cAMP) levels, and promotes cell detachment. Granules, release a series of biologically active substances such as bradykinin, histamine, etc., causing smooth muscle spasm of the gastrointestinal tract, increased telangiectasia and permeability, causing hemorrhage and edema of tissues and organs.

Immune complex reaction type (25%):

When the allergen enters the human body, it produces the corresponding IgG type antibody. When the allergen enters the body again, it binds to the corresponding IgG to form an antigen-antibody complex; the latter activates the complement system, attracts neutrophils to phagocytose the immune complex, and releases The lysosomal enzyme is involved in the capillary wall of the skin, gastrointestinal tract, kidney and other organs, which increases the fragility and permeability, and the corresponding clinical manifestations appear.

Extensive capillary and arteriolar inflammation is the basic pathological disease of the disease, causing perivascular infiltration of the subcutaneous, submucosal and subserosal tissues and exudation of blood samples, mainly involving the skin, kidney, serosa, synovium, etc. Diffuse or focal glomerulonephritis changes.

Pathological changes (15%):

The disease may have corresponding pathological changes in different organs of the body. The main pathological changes of intestinal allergic purpura are inflammation of small blood vessels in the intestinal wall, neutrophils, lymphocytes and plasma cells around the blood vessels, and cellulose-like necrosis in the blood vessel wall. And platelet packing and interstitial edema, mucosal edema of the intestine with bloody exudate or hemorrhage, or intussusception due to irregular bowel movements, such as skin lesions mainly in the dermal layer of blood vessels, IgG and C3 around the blood vessels Presenting purpura and urticaria, kidneys are mostly glomerular focal lesions in time, varying in severity. Fluorescence microscopy shows a large amount of fibrin on the glomerular basement membrane, complement and antibody (mainly IgA), serious condition At the glomerular capillaries, focal necrosis, proximal tubular epithelial cell swelling and vacuolization may occur, and the disease may even affect the heart, lungs and cerebral blood vessels, causing damage to the corresponding organs.

Small intestinal allergic purpura prevention

1, pay attention to avoid contact with pathogens, such as pollen, chemicals, paint, gasoline, dust mites and so on.

2, children with allergies do not need to raise pets, try to reduce contact with animal skin, especially those who have already identified allergens should pay more attention.

3, pay attention to food hygiene, wash hands frequently, do not eat unclean fruits and aquatic plants, in order to eliminate the chance of intestinal parasite infection.

4, strengthen exercise, enhance physical fitness, improve the body's immunity to various infections, to avoid the cause of allergic purpura.

5, pay attention to climate change, timely increase or decrease clothes, prevent colds, regular ventilation in the room to keep the indoor air fresh.

6, before the condition has not healed, do not vaccinate various preventive vaccines, must be cured after 3-6 months, can be vaccinated, otherwise it may lead to the recurrence of the disease.

Small intestinal allergic purpura complications Complications, intussusception, intestinal obstruction

Intestinal intussusception, intestinal obstruction or perforation may occur in patients with severe intestinal allergic purpura.

Intestinal allergic purpura symptoms common symptoms skin purpura fatigue nausea loss of appetite acute abdomen intussusception edema joint pain proteinuria renal failure

The typical manifestations of this disease can affect the skin, gastrointestinal tract, joints and kidneys. Four of them can appear alone or in combination with one organ.

Most patients have general symptoms such as general malaise, fatigue, loss of appetite, headache, fever or upper respiratory tract 1 to 2 weeks before onset. Skin purpura is the most common clinical symptom, and the pressure is not faded. Most of it is distributed in the limbs and buttocks. It is more common in the extremities of both lower extremities. It can be expressed as urticaria, then it turns into bright red purpura, and gradually turns into dark red. The skin spots and spots are different in size and can be scattered or merged into pieces. Severe can be fused into bullae or central necrosis, some may be associated with angioedema, erythema erythema and other skin allergic manifestations.

Intestinal allergic purpura is mainly characterized by abdominal pain. The pain is different, accompanied by nausea and vomiting. In severe cases, it may be colic, or even intussusception, intestinal obstruction or perforation. Some children may be involved in the gastrointestinal tract. Or acute abdomen as the first symptom, followed by hematuria or purpura, surgical exploration can be found in the empty ileum significantly dilated, edema with punctiform dark red lesions, or intestinal necrosis, etc., these lesions are plasma exudate into the intestinal wall And caused by irregular bowel movements.

Others may also have symptoms such as joints and kidneys. The former is more common in large joints, and there are exudates around the joints, which are characterized by joint pain and swelling. After the symptoms subsided, there are no sequelae. The kidney lesions are different in severity. For a short period of hematuria and a small amount of proteinuria, disappeared with the improvement of lesions after weeks or months; severe cases soon after the appearance of hematuria, quickly developed into renal failure, a small number of patients can develop chronic nephritis.

Examination of intestinal allergic purpura

1. Peripheral blood: Eosinophils and neutrophils, platelets are usually normal, various hemostasis, the results of coagulation tests are normal.

2. Capillary fragility test: Half of the patients were positive for capillary fragility test.

3. Fecal occult blood test: can be positive or strong positive.

4. Urine routine: visible red blood cells, protein, cast.

5. Serum antibody examination: serum IgE levels can be increased, and blood IgA is increased in 50% of cases.

6. B-mode ultrasonography: It is helpful for the diagnosis of allergic purpura in the small intestine, which is characterized by exudation in the intestinal wall and asymmetry and low echogenicity of the intestinal wall.

7. Endoscopy and biopsy: the intestinal wall may have eosinophil infiltration.

8. Bone marrow examination: The bone marrow examination is normal.

Diagnosis and differential diagnosis of intestinal allergic purpura

According to the pre-onset symptoms, typical skin purpura and abdominal symptoms appear, and it is generally not difficult to diagnose the disease.

However, if there is only abdominal symptoms without skin purpura, it should be differentiated from acute abdomen caused by various causes. People with joint pain or proteinuria should also be associated with rheumatoid arthritis or acute and chronic glomerulonephritis. In the differential diagnosis, a small number of patients should be differentiated from cerebrovascular accidents and brain occupying lesions when the lesions involve the cerebrovascular and meningeal vessels and cause neurological symptoms or intracranial hemorrhage.

The material in this site is intended to be of general informational use and is not intended to constitute medical advice, probable diagnosis, or recommended treatments.