A Case of Persistent Aortic Graft and Retroperitoneal Enhancement on FDG PET/CT

A 39-year-old woman presented to the emergency room with worsening left flank pain, low-grade fever, and chills. Five months prior she underwent open aortic repair for a ruptured type 4 thoracoabdominal aortic aneurysm from an unknown etiology. The physical examination was normal except for diffuse abdominal tenderness to deep palpation. Laboratory testing revealed white blood cells (WBC) 15.8 K/mcL (ref 4.5–11.0), erythrocyte sedimentation rate (ESR) 70 mm/hour (ref 0–23), and C-reactive protein (CRP) 107 mg/L (ref 0–10). Blood cultures showed no microbial growth, and urine analysis was unremarkable. CT abdomen and pelvis displayed a new retroperitoneal fluid collection that was suggestive of a hematoma with peripheral enhancement. Subsequent FDG (fluorodeoxyglucose) PET/CT (positron emission tomography/computed tomography) demonstrated significant radiotracer uptake surrounding the entire abdominal aortic graft as well as within the retroperitoneal fluid collection, highly concerning for an infectious process (Figure 1). Aspiration of the retroperitoneal collection revealed serosanguinous fluid and no aerobic or anaerobic bacterial growth occurred over 5 days. Next-generation RNA sequencing from this aspiration was negative for any bacterial, fungal, or mycobacterial RNA. 1,3-beta-D-glucan, serum galactomannan, QuantiFERON®-TB Gold and serum next-generation sequencing for microbial cell-free DNA were all negative.