Aims Aortitis is a rare but important cause of thoracic aortic disease. We describe its histopathological patterns and associations with other aortic pathologies and systemic inflammatory disease.

Methods Database searches of thoracic specimens over 17 years from two centres yielded 71 cases of non-infectious aortitis. Histological verification of tunica media inflammation was required for inclusion. Clinical information and histopathological features were recorded.

Results Three histological patterns emerged—necrotising aortitis with giant cells (53), diffuse band-like aortitis (16) and ‘other’ (2). 50/53 cases of necrotising aortitis with giant cells were isolated/idiopathic, while 9/16 cases of diffuse aortitis had a systemic inflammatory disease. Medial degeneration (MD) was prominent in 23/71 cases—all in the necrotising aortitis with giant cells category.

Conclusions Non-infectious aortitis is predominantly idiopathic/isolated in nature, occurring in elderly females. Two patterns emerge—(1) necrotising aortitis with giant cells, which is more likely to be idiopathic and linked to MD, suggesting a possible aetiological relationship; and (2) diffuse aortitis, which is linked to an increased risk of systemic inflammatory disease. Knowledge, therefore, of histopathological patterns may guide patient management and follow-up.