RESUMEN
Wiskott Aldrich syndrome (WAS) is an X-linked primary immunodeficiency, associated with WASP gene mutation that causes severe immunological abnormalities and alterations in platelet function. A seven year old male patient with WASP, began with acute abdominal pain, fever and knee swelling. The diagnosis of septic arthritis was made, and he was treated with broad-spectrum antibiotics and human gammaglobulin. During treatment he presented digestive tract bleeding with hypovolemic shock; after 72 hours palpable purpura in upper and lower extremities appeared. Then Henoch-Schönlein purpura with abdominal vasculitis was suspected, and later confirmed by histopathology. Methylprednisolone pulses were initiated, showing improvement within 24 hours. The patient had a severe inflammatory reaction, caused by a serious infectious disease, but the clinical evolution suggested an autoimmune disease such as Henoch-Schönlein purpura. Up to 20% of patients with WAS have autoimmune manifestations of vasculitis. An early diagnosis of autoimmunity in WAS is important for a favorable clinical outcome.