Contained ruptured paravisceral aortic aneurysm related to immunoglobulin G4 aortitis.

BACKGROUND

To describe a case of autoimmune inflammatory abdominal aortic aneurysm (AAA) associated with rupture.

METHODS

A 63-year-old woman presented with 5 days of abdominal pain, malaise, fever, and chills after 6 months of debilitating back pain with a 3-kg weight loss. On examination, she was shown to have a tender palpable pulsatile abdominal mass. Computed tomographic angiography revealed a multilobulated paravisceral AAA (5.5 cm in maximal diameter) and bilateral popliteal aneurysms. The appearance of the aneurysms was indicative of primary aortic infection. Laboratory examinations demonstrated a white blood cell (WBC) count of 12.3×10(9)/L, erythrocyte sedimentation rate of 131 mm/hr, normal antinuclear antibody level, and C-reactive protein level of 211 mg/L. Nuclear WBC scan showed no uptake of tracer around the aorta. Blood and urine cultures were negative. Because of the AAA size and symptoms, open repair was expedited. The operation was performed through a transabdominal midline incision with a mediovisceral rotation. Extensive retroperitoneal inflammation extending into the paravisceral aorta was encountered. Supraceliac clamping was possible. The aorta was replaced from the level of the superior mesenteric artery to the aortic bifurcation with a 16-mm rifampin-soaked graft with reimplantation of the left renal artery. Cultures and biopsies were done.

RESULTS

Histology demonstrated vessel wall rupture, adventitial fibrosis and inflammatory cell infiltration, obliterative phlebitis, lymphoid follicles, perineural inflammation, and immunoglobulin G4 (IgG4) plasma cell infiltration, consistent with a contained ruptured aneurysm associated with IgG4 periaortitis. The patient had a long postoperative course with prolonged intubation and renal failure requiring hemodialysis, which resolved 8 weeks postoperatively. Immunosuppression was paramount for her improvement.

CONCLUSION

IgG4-related inflammatory AAAs are rare; this is the first report of one with a contained rupture. The patient's symptoms, the unusual appearance on computed tomography, the presence of popliteal aneurysms in a woman, and the normal WBC scan were indicative of an inflammatory etiology. Tissue biopsy was critical to obtain histological diagnosis and direct treatment.