Immune Checkpoint Inhibitor–Associated Perigraft Aortitis of an Ascending Aortic Dacron Graft: a Case Report

Background Immune checkpoint inhibitors (ICI) can trigger large-vessel vasculitis, including aortitis. Perigraft involvement is rare and may closely mimic prosthetic graft infection, a distinction with major therapeutic implications. Case Summary A 68 year old woman with a supracoronary ascending aortic Dacron graft and c-KIT–mutated mucosal melanoma treated with ipilimumab–nivolumab underwent restaging 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT), which revealed new FDG-avid soft tissue abutting the graft (SUVmax ≈6.3), absent on all pre-ICI imaging. Contrast-enhanced CT showed a thin circumferential inflammatory cortex; transoesophageal echocardiography confirmed an intact graft without structural complications. The patient was persistently afebrile; blood cultures and procalcitonin were negative. After ICI discontinuation and high-dose corticosteroids, serial PET/CT demonstrated progressive metabolic improvement, with complete resolution at 20 months. Nivolumab was later cautiously reintroduced without complications. Discussion Published experience with ICI-aortitis is limited to small series and case reports. This case provides evidence for ICI-mediated perigraft aortitis based on temporal association, response to de-challenge and immunosuppression, multimodality imaging, complete resolution, and thorough exclusion of infection. Conservative management is feasible in stable patients, reserving surgery for structural complications.