Ruptured intrahepatic aneurysm as the initial manifestation of polyarteritis nodosa

Polyarteritis nodosa (PAN) is characterized by panarteritis involving all l ayers of the vessel wall of medium and small arteries and adjacent veins le ading to thrombosis and aneurysmal dilatation. We present the case of a 21- year-old Caucasian man with an acute abdomen with a massive gastrointestina l (GI) hemorrhage caused by a large intrahepatic aneurysmal rupture needing surgery. This was the initial manifestation of underlying PAN, which had n ot been diagnosed before the event. This patient's postoperative course was complicated by continued hemorrhage prompting further diagnostic abdominal arteriography, which revealed multiple aneurysms along the superior mesent eric artery. The aneurysmal wall biopsy revealed lymphocytic infiltrates, s cattered giant cells, and minimal necrosis. A diagnosis of PAN was entertai ned based on arteriographic findings, although no pathognomonic demonstrati on of multiple visceral aneurysms is a characteristic finding of PAN. The p atient survived the catastrophic event, and treatment with corticosteroids was initiated, which led to an uncomplicated hospital stay. Furthermore, ou tpatient follow ups showed continued clinical improvement with corticostero id therapy and a repeat angiogram performed elsewhere demonstrated resoluti on 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 increa sed mortality. The clinical significance of abdominal pain is not always ap parent. It may occur in the absence of any gross intra-abdominal lesions, o r, as in our patient, may herald an acute abdominal catastrophe. The clinic ian should consider PAN in the differential diagnosis of a massive GI hemor rhage. It is also important to note that early diagnosis followed by aggres sive treatment can be lifesaving.