Pseudotumour formation in atheromatous coronary arteries.

Three cases with mass like lesions (pseudotumours) surrounding atheromatous coronary arteries were referred to the Royal Brompton Hospital for expert pathology review. All were males with mean age 74 years (range 55-91). In all cases, coronial autopsies were carried out for sudden deaths in the community. Past medical histories of note were hypertension (N = 2) and ischaemic heart disease (N = 1), with one patient having a past history of aortic aneurysm repair. At autopsy, firm, white and whorled masses surrounded both right and left coronary arteries ranging in size from 9 to 25 mm in diameter. Each coronary artery had intimal atheroma with associated stenosis ranging from moderate to severe. A thrombus was identified in one case. Histological sections showed a mixed inflammatory infiltrate extending from the media into the adventitia of each coronary artery, composed predominantly of plasma cells and lymphocytes with rare neutrophils and eosinophils. There was accompanying dense fibrosis accounting for approximately 50% of the mass size on microscopic examination of slides. The presence of intimal circumferential atheroma was confirmed in all cases. Immunohistochemical studies showed staining with IgG4 in two of three cases. Atheroma may be associated with mild chronic inflammation present in the intima or associated with plaques and adventitia. The differential diagnosis for coronary artery inflammatory masses would include vasculitis, syphilis, inflammatory pseudotumor and IgG4 associated disease. This is the first report of isolated coronary artery IgG4 related disease in association with atheroma.