BACKGROUND Lymphoplasmacytic thoracic aortitis is still underrecognized cause of thoracic aortic aneurysm. METHODS We herein report a case of symptomatic inflammatory ascending aortic aneurysm and pericarditis diagnosed on CT scan as acute type A intramural hematoma. Patient underwent emergency supracoronary ascending aorta replacement with a prosthetic graft. Marked inflammatory thickening of aneurysm wall was the intraoperative finding. Histopathologic examination of the excised aortic tissue showed inflammation with lymphoplasmacytic pattern of aortitis. CONCLUSIONS This case demonstrates that lymphoplasmacytic aortitis may mimic symptoms and radiological findings of intramural hematoma.