Segmental mediolytic arteritis--electronmicroscopic and immunohistochemical study

Fatal hemoperitoneum due to segmental arterial mediolysis

Spontaneous hemoperitoneum due to vascular injury is a life-threatening condition mostly associated with aortic or splanchnic arterial disease, which stems from atherosclerotic, inflammatory, or infectious origin. However, in 1976, Slavin and Gonzales described a nonatherosclerotic arterial disease that may render aneurysmal formation predominantly in the splanchnic arterial bed. The clinical presentation is diverse, but abdominal pain and shock prevail. We report the case of a middle-aged man who presented a hemoperitoneum due to a middle colic artery aneurysm rupture and died after undergoing a surgical treatment attempt. The preoperative imaging study revealed the presence of a huge hematoma in the epiplon retrocavity, and abdominal free liquid as well as extensive arterial disease with multiple aneurysms. The autopsy findings included hemoperitoneum, hematoma in the upper left abdominal quadrant, the surgical ligature of the middle colic artery, and histologic features consistent with segmental arterial mediolysis. The authors call attention to this rare entity and highlight the autopsy as a fundamental examination to accurately reach this diagnosis.

Systemic lupus erythematosus with hepatic aneurysm, Valsalva sinus aneurysm and associated polyangiitis: aneurysmal wall remodeling with dense fibrosis and calcification mediated by residual smooth muscle cells

Isolated case reports have demonstrated the combination of hepatic aneurysm and systemic lupus erythematosus (SLE). The author experienced a rare autopsy case of a 36-year old Japanese male with SLE, a hepatic aneurysm, a Valsalva sinus aneurysm and associated polyangiitis. In the histopathological and ultrastructural examinations of the postmortem organs, most of the angiitis lesions were in the scar phase associated with the histopathological features of collagenous fibrosis with the diminution of the smooth muscle cells and elastic fibre layers. Massive calcification was seen on the wall and obliterative changes in the lumen with calcified thrombi. In the dense collagenous stroma of the aneurysmal wall, residual atrophic smooth muscle cells with immunohistochemical (HHF35, alpha-smooth-muscle actin, vimentin and desmin almost-) and ultrastructural features (spindle-shapedcells with a few rER and rich intracytoplasmicfilaments with peripheraldense patches)were assumed to be involvedin the histogenesisof the aneurysmalwall. Massivecalcification and degenerationor dynamic remodelingof the extracellularmatrices in the aneurysmalwall might be mediated by the residual smooth muscle cells. It was suspected that the generalized polyangiitis as a complication of SLE might have involved the intrahepatic arteries and Valsalva sinus wall and subsequently generated the aneurysm.

Systemic, cerebral, and pulmonary segmental mediolytc arteriopathy: Villainous masqueraders of vasculitis

Segmental mediolytic arteriopathy (SMA) is a newly described and uncommon variant of arterial fibromuscular dysplasia that affects principally visceral small and medium sized arteries. SMA is characterized by myolytic dysplasia of the arterial media, intramural dissection, and thrombosis or ruptured aneurysms resulting in visceral hemorrhage and infarction as the dire consequences. Because of its relative obscurity and frequent angiographic manifestation of microaneurysms, clinically SMA mimics polyarteritis nodosa, and the patient so diagnosed had been treated with immunosuppressive therapy with a catastrophic outcome. Five new cases of unsuspected SMA are described herein, three involving visceral arteries and, for the first time, one case each affecting the cerebral and pulmonary parenchymal arteries. Three of the five patients did not survive because SMA remained unrecognized until after death and a subsequent review of the biopsy and autopsy specimens. Death in each of the three patients was directly attributable to complications of SMA or indirectly to septic complications of the immunosuppressive therapy for the misdiagnosed vasculitis. Clinicians and pathologists alike should become better acquainted with this unusual form of noninflammatory arteriopathy, so as not to misdiagnose it as vasculitis.

Segmental arterial mediolysis: report of 2 cases and review of the literature

Segmental arterial mediolysis (SAM) is an idiopathic noninflammatory vasculopathy involving small to medium arteries, usually in the abdomen, although arteries in the cerebral and coronary circulations also may be affected. Some cases present as abdominal apoplexy due to aneurysmal rupture, but ischemia and infarction also occur. Not uncommonly, SAM may be misdiagnosed as a systemic necrotizing vasculitis. We present 2 patients with bilateral renal infarctions, cerebral arterial dissections, and visceral artery microaneurysms. Both were diagnosed initially as polyarteritis nodosa. The diagnosis was changed to SAM, in one case based on clinical and radiologic features, and in the other, on an open wedge kidney biopsy. We discuss the differential diagnosis and review the literature on SAM.

Pulmonale segmentale mediolytische Arteriopathie

Segmental mediolytic arteriopathy (SMA) is defined as non-inflammatory arteriopathy with mediolysis due to segmental loss of media and consecutive formation of vascular gaps. Up to now, less than 40 cases of visceral and cerebral SMA and, to our knowledge, only one case of pulmonary SMA have been reported. We present the history of a 21 year old female patient, admitted to hospital with hemoptysis, but without other symptoms. Apart from two lesions in the sixth and tenth pulmonary segment, documented by CT and interpreted as colliquations, there were no other clinical and laboratory findings. Repeated bronchoscopy supplied no further information. Histomorphology of the resected lesion revealed SMA without evidence of vasculitis. Wegener's disease could be excluded. The aetiology of the disease is still unknown. Acute vasospasm (due to inappropriate reactions to catecholamine or endothelial dysfunction), as well as SMA as a precursor or subtype of fibromuscular dysplasia, are two theories still under discussion.

Bilateral extensive cerebral infarction and mesenteric ischemia associated with segmental arterial mediolysis in two young women

Segmental arterial mediolysis (SAM) is a rare non-atherosclerotic non-inflammatory vascular disease that affects mainly muscular arteries of the splanchnic and cerebral territories. Reported herein are two cases of SAM in young women with fatal outcome. One of the patients had an atypical form of the disease, which primarily affected small intestinal submucosal and subserosal arteries, and resulted in acute mesenteric ischemia. The other had bilateral brain infarction with SAM of internal carotid arteries (ICA). Pathological examination of both cases did not reveal the cause of blood flow disturbance: large mesenteric branches of the former and ICA of the latter were free of either dissection or thrombosis; in addition, small intestinal arteries of the first patient did not show signs of vasculitis. These findings suggest that unusual pathways of arterial occlusion and dissection may occur in the context of SAM.

Segmental mediolytic arteritis [correction of arteries]: a case report with review of the literature

Segmental mediolytic arteritis is a very rare vascular disease which causes sudden intraabdominal hemorrhage. The disease is characterized by degeneration of the arterial media, followed by aneurysmal dilatation and rupture of the involved artery. Up to now, only 13 cases have been reported, and this unique disease is not fully recognized among general pathologists and physicians. Here, we present a case of segmental mediolytic arteritis involving the propria hepatic artery, which resulted in intraabdominal hemorrhage, and consequently hypovolemic circulatory disturbance. Histologically, the rupture focus showed degeneration and desquamation of the intima and media with fibrin-like material covering the exposed adventitia. Inflammatory infiltrates were only noted in the rupture focus as a secondary reactive change. Other than the rupture focus, there were two foci showing similar findings. This disease has rarely been reported and is seldom recognized as a cause of arterial rupture. In cases of sudden intraabdominal hemorrhage, segmental mediolytic arteritis should be considered as a possible cause in addition to atherosclerotic and mycotic aneurysm, traumatic injury and vasculitis syndromes.

Ruptured inferior mesenteric artery aneurysm due to segmental mediolytic arteritis

Segmental mediolytic arteritis is a rare non-inflammatory arteriopathy. Only eight cases have been reported so far. The authors report a case of a ruptured inferior mesenteric artery aneurysm due to segmental mediolytic arteritis in which preoperative angiography revealed lesions and successful surgical treatment was performed. A review of the clinical features of segmental mediolytic arteritis is also presented.