2014 Ultrastructural Pathology, 2014; 38(3): 199–203 ! Informa Healthcare USA, Inc. ISSN: 0191-3123 print / 1521-0758 online DOI: 10.3109/01913123.2013.868568 ORIGINAL ARTICLE Internal Mammary Artery Atherosclerosis: An Ultrastructural Study of Two Cases Ida Perrotta, PhD 1 , Alfonso Sciangula, MD 2 , Giovanni Concistre `, MD 2 , Dr. Sergio Mazzulla 1 , Prof. Saveria Aquila 3 , and Alfonso Agnino, MD 2 1 Department of Biology, Ecology and Earth Science (Di.B.E.S.T.), University of Calabria – Arcavacata, Rende, Cosenza, Italy, 2 Department of Cardiothoracic Surgery and Cardiology, Sant’Anna Hospital, Catanzaro, Italy, and 3 Department of Pharmacy and Sciences of Health and Nutrition, Centro Sanitario, University of Calabria, Arcavacata, Rende, Cosenza, Italy ABSTRACT Atherosclerosis of the internal mammary artery (IMA) is generally regarded as a rare (but existent) pathological entity with only a few cases reported in the most recent literature. The only study which to our knowledge has investigated the ultrastructural features of IMA atherosclerosis, demonstrate the presence of endothelial cells loss, defects of internal elastic lamina with no evidence of lipid accumulation. In the present study, we describe two cases of IMA atherosclerosis in which ultrastructural analysis revealed the presence of a typical atherosclerotic plaque morphology with infiltration of inflammatory cells, formation of intraplaque lipid pools, and accumulation of lipid-laden foam cells throughout the thickened intima, never described in this rare lesion before. Microscopically, the lesions were also characterized by intimal thickening, invagination of endothelial cells, migration of smooth muscle cells with splitting, fenestration and/or fragmentation of the elastic sheets. Our observations add new data to the scarce and contradictory literature and to this largely understudied vascular disorder. Keywords: Atherosclerosis, electron microscopy, internal mammary artery The internal mammary arteries (also called IMA grafts or internal thoracic arteries) like the coronary arteries are intrathoracic vessels of comparable size and structure also subjected to the same intrapleural pressure. The IMAs have been used frequently for myocardial revascularization by virtue of their resist- ance in developing atherosclerosis both before and after bypass grafting as well as control tissues in studies related with the development of atheroscler- otic and restenotic lesions [1,2]. Although considered relatively rare, atherosclerosis of the IMAs can occur and, if undetected, can jeopardize the result of the coronary bypass surgery posing a high risk to human life. Despite the number of clinical reports, mostly dealing with the incidence and outcome of IMA atherosclerosis, the structural and micromorphologi- cal features of these lesions are still largely unknown with only incomplete and fragmentary information published in the scientific literature [3–8]. Therefore, the present study was designed to elucidate the ultrastructural nature of the disease in the ‘‘atherore- sistant’’ native IMAs obtained from individuals undergoing coronary bypass procedures throughout a morphological analysis of tissue damage both at light and electron microscopic levels. STUDY MATERIALS In the last two months, a 65-year-old male and a 72-year-old female with a history of hypertension and hypercholesterolemia, both suffering from unstable angina and extracardiac arteriopathy, were scheduled for coronary artery bypass graft surgery with IMAs at Correspondence: Dr Ida Perrotta, Department of Biology, Ecology and Earth Sciences, Laboratory of Electron Microscopy, Cubo 15A, University of Calabria, Arcavacata di Rende (CS) 87036, Italy. Tel: þ39(0)984 493632. E-mail: idaperrotta@yahoo.it Received 18 September 2013; Revised 4 November 2013; Accepted 11 November 2013; Published online 27 January 2014 199