Polyarteritis nodosa. An unusual cause of acute abdomen.

Two cases of acute abdomen operated on twice and biopsy specimens confirmed are presented. The diagnosis of a systemic necrotizing vasculitis group of polyarteritis nodosa was established. The syndrome affects predominantly males between the second and forth decade of life. The gastrointestinal tract is involved in approximately 50% of the cases. While a negative laparotomy may be considered as a surgical pit-fall, nevertheless, it is the only way of establishing the diagnosis and treating the complications of the disease in some of the cases.