bubble_chart Overview

Allergic Purpura Syndrome, also known as Schonlein-Henoch purpura or Hemorrhagic Capillary Toxicosis, is a systemic hemorrhagic disease caused by microvascular allergic reactions, which can affect the skin, joints, gastrointestinal tract, and kidneys, leading to corresponding symptoms. This condition is most commonly seen in children and adolescents.

bubble_chart Etiology

The etiology of this disease is unclear and may be related to multiple factors: ① Infectious factors. The disease often occurs after acute infection following a certain incubation period, mostly due to acute upper respiratory infections. The pathogens are mainly hemolytic streptococci, but may also include Staphylococcus aureus, viruses, and infections by Chinese Taxillus Herb insects. ② Food allergies, such as allergies to foreign proteins like fish, shrimp, crab, and milk, can trigger the disease. ③ Medications, such as penicillin, streptomycin, sulfonamides, and salicylate preparations. Additionally, it may be associated with factors like cold exposure, insect bites, and contact with Mongolian snakegourd root dust. These factors cause inflammatory changes in small arteries, small veins, and capillary walls in the human body, increasing vascular permeability and leading to exudative hemorrhage and edema in subcutaneous tissues, mucous membranes, and organ blood vessels, resulting in corresponding clinical manifestations.

bubble_chart Pathological Changes

There is infiltration of lymphocytes and plasma cells around the cutaneous blood vessels, with inflammatory changes in the capillaries of the dermis, leading to exudation, edema, hemorrhage, and resulting in skin purpura. Edema, exudation, and hemorrhage in the intestinal mucosal layer are the causes of abdominal pain. Joint pain is primarily due to edema around the joints and exudation in the joint cavity. Kidney involvement may manifest as glomerular cell proliferation, focal necrosis, capillary thrombosis, as well as swelling and degeneration of renal tubular epithelial cells, and interstitial fibrosis.

bubble_chart Clinical Manifestations

The onset is often preceded by a history of upper respiratory tract infection 1–3 weeks prior, with a slow progression and a prolonged course, frequently characterized by alternating episodes of flare-ups and remissions. Clinical manifestations vary depending on the affected sites:

1. **Skin manifestations**: Most cases present with skin purpura as the initial symptom. It commonly appears on the extensor surfaces of the distal limbs, buttocks, and back, while the face and trunk are less frequently involved. The purpura is symmetrically distributed, occurs in batches, varies in size, and may merge into patches or even form hemorrhagic vesicles and necrotic lesions. The purpura typically resolves spontaneously within a few days. A minority of cases may also present with vascular edema or urticaria on the eyelids, lips, hands, or feet.

2. **Gastrointestinal changes**: Abdominal symptoms often follow skin purpura, though gastrointestinal symptoms may occasionally be the initial presentation. The main features include episodic colicky pain or persistent dull pain around the umbilicus or lower abdomen, accompanied by nausea and vomiting. Severe cases may present with hematochezia, hematemesis, intussusception, or intestinal perforation. Physical examination may reveal abdominal tenderness but no muscle guarding or rebound tenderness. When abdominal symptoms dominate, it is termed **Henoch Purpura (abdominal type)**.

3. **Joint manifestations**: These include redness, swelling, and pain in the joints of the limbs, most commonly the knees, ankles, elbows, and wrists. The symptoms are often migratory, resolving within days but prone to recurrence, and may be accompanied by low-grade fever during flare-ups. When joint symptoms are prominent, it is referred to as **Schonlein Purpura (arthritic type)**.

4. **Renal manifestations**: Kidney involvement typically follows the appearance of purpura, presenting as proteinuria, hematuria, or cylindruria. Some patients may also develop edema, oliguria, or hypertension. In most cases, renal damage resolves well without sequelae, though a minority may progress to chronic nephritis or even uremia. Notably, some cases may primarily exhibit renal involvement with minimal or no purpura.

Additionally, vascular exudative bleeding and edema may affect the nervous system, respiratory tract, or other organs, leading to corresponding symptoms.

bubble_chart Auxiliary Examination

Bleeding time, clotting time, platelet count, and function are normal, while the erythrocyte sedimentation rate may be normal or show grade I acceleration. Some patients may test positive for capillary fragility (tourniquet test). Those with kidney involvement may exhibit proteinuria, hematuria, and cylindruria.

bubble_chart Diagnosis

The presence of skin purpura following an upper respiratory infection, along with simultaneous involvement of the joints, abdomen, and kidneys, and a tendency for recurrence, should raise suspicion of this condition. However, it is important to differentiate it from thrombocytopenic purpura, acute abdomen, glomerulonephritis, and rheumatoid arthritis.

bubble_chart Treatment Measures

1. Eliminate disease causes: including anti-infection, removal of infected foci, clearing intestinal parasites, and avoiding allergenic foods and medications.

2. Antihistamines: Options include chlorpheniramine, promethazine, diphenhydramine, or astemizole for oral or intramuscular administration. Alternatively, 10% calcium gluconate 10ml can be administered intravenously, once or twice daily.

3. Glucocorticoids: Suitable for acute phases and cases with significant abdominal or joint pain, as they rapidly alleviate symptoms. Oral prednisone may be prescribed, or intravenous hydrocortisone if necessary. Short-term use (3–5 days) can be discontinued after symptom relief, but prolonged use requires gradual tapering before stopping.

4. Others: Bed rest is advised during the acute phase, and fasting is recommended for those with severe gastrointestinal symptoms. High-dose intravenous vitamin C (3–5g/day) may be administered. For severe abdominal pain, intramuscular atropine 0.5–1mg can be given. Hemostatic agents may be used for bleeding tendencies. For patients with kidney damage.