Extensive cardiac allograft vasculitis and concurrent fat necrosis 6 years after orthotopic heart transplantation.

Coronary artery vasculitis has been described as a rare lesion in the spectrum of transplant vasculopathy or as an extension of severe acute cellular rejection. We describe a patient, 6 years after orthotopic cardiac transplantation, who developed rapid heart failure and died despite aggressive treatment, minimal cardiac rejection (ISHLT Grade 1R), and no known transplant vasculopathy. Autopsy showed a diffuse and essentially complete necrotizing vasculitis of the entire coronary vasculature involving small, medium and large vessels, with extensive fat necrosis within the pericardial space. Macrophages of the M2 phenotype were found lining the major coronary vascular lumens and infiltrating their walls. The presence of the M2 macrophage phenotype supports transplant vasculitis as part of the chronic transplant vasculopathy continuum.