Fibrin-associated large B-cell lymphoma around vascular prosthesis mimicking recurrent abdominal aortic aneurysm

A 67-year-old man presented to our hospital for examination of an enlarged abdominal aortic aneurysm (AAA) 6 years after endovascular aortic repair with Powerlink (Endologix). Contrast-enhanced computed tomography (CT) showed a 79-mm infrarenal AAA (Figure 1, A). Endoleaks were not detected on 4-dimensional CT. Therefore, a type V endoleak was considered to be present. Aortic replacement with a Y-shaped vascular prosthesis (Gelsoft Plus; Terumo Aortic) was performed. However, the aneurysmal sac covering the vascular prosthesis became enlarged subsequently, which caused the vascular prosthesis to be compressed forward, resulting in the narrowing of its lumen 3 years after aortic replacement (Figure 1, B, and Video 1). He was suggested to undergo surgical aortic repair but refused additional treatment. Therefore, CT-guided drainage within the aneurysmal sac was planned to confirm the diagnosis. Although we believed that there was no blood flow within the aneurysmal sac because of no-contrast effect on CT, we planned on performing emergency surgery if the AAA ruptured. CT-guided needle biopsy showed approximately 80 mL of dark-red drainage fluid, and cytology by cell block method revealed large, atypical lymphocytes (Figure 1, C). Immunostaining demonstrated that the sample was positive for CD20 (Figure 1, D), CD79a, MUM1, and BCL2 and negative for CD3 (Figure 1, E), CD5, CD10, BCL6, and human herpesvirus-8. The lymphoma cells were also positive for EBV. Encoded RNA in situ hybridization (Figure 1, F) contributed to the diagnosis of FA-LBCL. Fluorodeoxyglucose-positron emission tomography/CT showed mild uptake around the vascular prosthesis, indicating an inflammatory state. The patient declined redo aortic replacement and underwent 6 cycles of rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone chemotherapy. The aneurysmal sac continues to enlarge 2 years after diagnosis.

FA-LBCL is uncommon, and only 10 cases of FA-LBCL associated with vascular prostheses have been reported in the literature^{,  ,  ,}  (Table 1). In general, FA-LBCL does not present with specific symptoms, and favorable clinical outcomes have been reported with surgical resection alone. However, FA-LBCL arising in vascular prostheses causes thromboembolic events such as cerebral infarction or lower-limb ischemia, as well as anastomotic pseudoaneurysms or multiple visceral aneurysms, which lead to aneurysm rupture and death. The optimal treatment for FA-LBCL within vascular prostheses has not been established; 2 of 5 cases with surgical resection resulted in recurrent disease and 1 of 3 cases treated with surgical resection followed by adjuvant chemotherapy revealed persistent disease. Two patients who did not undergo replacement of vascular prosthesis died from aneurysm rupture or thromboembolism. In our case, FA-LBCL was found around the vascular prosthesis, and it could not be confirmed with any degree of certainty that the aneurysmal sac enlargement after endovascular aortic repair was caused by FA-LBCL because histopathologic examination was not performed. It mimicked perigraft seroma or recurrent AAA after aortic replacement, and differentiation based on image findings alone was difficult because of the high intraluminal pressure of the aneurysmal sac that was expected from the enlargement of the aneurysmal sac and narrowing of the vascular prosthesis. The tumor has been growing after completion of a course of rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone chemotherapy, indicating that the lesion may be immunologically isolated and might be rendering chemotherapy ineffective. We believe that the optimal management plan would be tumor resection and a new aortic prosthesis replacement. In patients with apparently idiopathic persistent enlargement of the aortic aneurysmal sac after aortic replacement, the possibility of perigraft FA-LBCL should be considered and appropriately investigated. Further evaluation is required to determine the overall clinical behavior and optimal treatment.