[An autopsy case of segmental mediolytic arteritis (SMA) accompanied with microscopic polyarteritis nodosa].

Segmental Mediolytic Arteritis (SMA) is a very rare arterial lesion which is limited in adults to the involvement of the intra-abdominal muscular arteries. The pathology is characterized by segmental disruption of the arterial media which leads segmental mediolysis, with subsequent dissecting aneurysm or rupture. A 73-year-old man was admitted to a hospital because of high fever, general fatigue and weight loss. These symptoms were resistant to antibiotic therapy, and soon after, renal insufficiency developed. Three months after the onset of symptoms, he died suddenly of hemorrhagic shock. Autopsy revealed rupture of the splenic artery and systemic necrotizing arteritis in the small-sized arteries of liver, pancreas and kidneys, as well as in the connective tissues around the adrenal glands. Histopathology of the splenic artery was consistent with SMA, and that of the systemic vascular lesions, with microscopic polyarteritis nodosa. Focal glomerular lesions characteristic of crescentic and/or granulomatous glomerulonephritis were present. A developmental mechanism for SMA is discussed with respect to this case together with a review of previous reports of this disease.