[Acute abdominal pain as the first sign of Henoch-Schönlein purpura; a hidden diagnosis in the absence of purpura].

2 girls with abdominal pain, aged 7 and 9 years, were admitted and underwent extensive evaluation: the first girl underwent colonoscopy and the second appendectomy, in which a negative appendix was removed. After 6 and 14 days, respectively, they developed skin lesions that did not disappear on pressure, characteristic of Henoch-Schönlein purpura (HSP). They recovered after treatment with prednisone. HSP is a systemic vasculitis, which can be diagnosed by its characteristic purpura of the skin. Diagnosis is more difficult if the patient does not present with skin lesions. HSP presenting with acute abdominal pain as an initial symptom can give rise to unnecessary additional investigation and even laparotomy. Apart from the other clinical features of HSP, i.e. bloody stools, oligo-articular arthritis and (microscopic) haematuria, diagnosis can be made earlier if biopsies of the normal skin or duodenum are taken and assessed for IgA depositions. Treatment of the abdominal pain with corticosteroids can be considered.