Allergic purpura is a syndrome caused by systemic vasculitis, characterized by the infiltration of blood components or plasma into the subcutaneous tissue, mucous membranes, and serous membranes, manifesting as skin petechiae, ecchymoses, joint pain, abdominal pain, and renal damage. The main triggers include bacterial and viral infections, as well as infestations by Chinese Taxillus Herb insects. It is also associated with allergens such as food and drugs. This condition can occur at any age but is more common in children and adolescents, with the highest incidence in spring. With the removal of triggers and appropriate drug treatment, the cure rate is relatively high. However, the disease is prone to recurrence, and patients with abdominal or renal types may experience more severe conditions. If complications or comorbidities occur, it can be life-threatening. Early diagnosis and treatment are emphasized in management to improve the cure rate.

bubble_chart Clinical Manifestations

1. Low-grade fever, headache, lack of strength, children often manifest as irritability;
2. Pinpoint or soybean-sized palpable petechiae and ecchymoses; severe cases may present with blood blisters, necrosis, and superficial ulcers;
3. Predominantly occurs on both lower limbs, especially the extensor surfaces of the calves;
4. The arthritic type may present with joint swelling and pain, with rashes often distributed around the joints;
5. The gastrointestinal type is often accompanied by vomiting, abdominal pain, and hematochezia;
6. The renal type may present with hematuria, proteinuria, and cylindruria.

bubble_chart Diagnosis

1. Recurrent palpable purpura predominantly distributed on the lower extremities;
2. Accompanied by abdominal pain, arthralgia, or hematuria, proteinuria, etc.;
3. Normal platelet count and coagulation time, with accelerated erythrocyte sedimentation rate;
4. Increased direct eosinophil count;
5. Pathological examination suggests leukocytoclastic vasculitis with fine stirred pulse;
6. Immunological tests show a specific elevation of IgA.

bubble_chart Treatment Measures

Treatment Principles

1. Identify and remove the disease cause, avoiding various inducing factors;
2. Non-specific anti-allergy treatment;
3. Reduce capillary permeability and fragility;
4. Corticosteroid and immunosuppressant therapy;
5. Surgical treatment may be performed for intussusception or intestinal perforation;
6. Symptomatic supportive treatment.

1. For early mild cases, oral antihistamines, vitamin C, vitamin E, rutin, and nicotinic acid are the main treatments;
2. For intermediate-stage [second-stage] ordinary cases, oral or intramuscular antihistamines, vitamin C, E, and intravenous calcium gluconate or small doses of corticosteroids are more effective;
3. For severe cases or those accompanied by joint, gastrointestinal, or kidney damage, moderate to high-dose intravenous corticosteroids are the main treatment, while supportive symptomatic therapy should also be noted;
4. For cases primarily involving kidney damage with poor response to hormones, cyclophosphamide, azathioprine, etc., may be tried;
5. For cases complicated by intussusception or intestinal perforation, emergency surgical intervention should be considered.

bubble_chart Cure Criteria

1. Cure: The rash completely disappears, with no arthralgia, abdominal pain, and negative urine test;
2. Improvement: Most of the rash subsides, with no other conditions such as arthralgia;
3. No cure: The rash does not subside or new rashes still appear, with persistent arthralgia, abdominal pain, positive urine protein or casts, and hematuria.