Urticaria caused by anaphylactoid purpura

Allergic purpura is mostly acute onset, and various symptoms can be presented in different order. The initial symptoms are mainly skin purpura, and a few cases are first manifested by abdominal pain, arthritis and renal symptoms. There is often a history of upper respiratory tract infection 1 to 3 weeks before onset, accompanied by low fever, lack of appetite, fatigue and systemic symptoms. Skin purpura: Repeatedly showing skin purpura is the characteristic of this disease, more common in limbs and buttocks, symmetrical distribution, extension side more, showed in batches, face and trunk less, initially purplish red spots papules, high skin surface, pressure does not fade, a few days can turn dark purple, eventually brown and fade. A small number of severe purpura can be fused into bullae accompanied by hemorrhagic necrosis, some cases can be accompanied by urticaria and angioneurotic edema, skin purpura generally subsided after four or six weeks, and some children relapsed several weeks or months later.