Ruptured intrahepatic aneurysm as the initial manifestation of polyarteritis nodosa.

polyarteritis nodosa (PAN) is characterized by panarteritis involving all layers of the vessel wall of medium and small arteries and adjacent veins leading to thrombosis and aneurysmal dilatation. We present the case of a 21-year-old Caucasian man with an acute abdomen with a massive gastrointestinal (GI) hemorrhage caused by a large intrahepatic aneurysmal rupture needing surgery. This was the initial manifestation of underlying PAN, which had not been diagnosed before the event. This patient's postoperative course was complicated by continued hemorrhage prompting further diagnostic abdominal arteriography, which revealed multiple art-eurysms along the superior mesenteric artery. The aneurysmal wall biopsy revealed lymphocytic infiltrates, scattered giant cells, and minimal necrosis. A diagnosis of PAN was entertained based on arteriographic findings, although no pathognomonic demonstration of multiple visceral aneu-rysms is a characteristic finding of PAN, The patient survived the catastrophic event, and treatment with corticosteroids was initiated, which led to an uncomplicated hospital stay. Furthermore, outpatient follow ups showed continued clinical improvement with corticosteroid therapy and a repeat angiogram performed elsewhere demonstrated resolution of most of the aneurysms. Our case represents an unusual initial clinical manifestation of PAN and is one of the few cases reported with a torrential (GI) hemorrhage resulting from a rupture of an intrahepatic aneurysm, which is associated with increased mortality. The clinical significance of abdominal pain is not always apparent. It may occur in the absence of any gross intra-abdominal lesions, or, as in our patient, may herald an acute abdominal catastrophe. The clinician should consider PAN in the differential diagnosis of a massive GI hemorrhage. It is also important to note that early diagnosis followed by aggressive treatment can be lifesaving.