Segmental arterial mediolysis is a vascular disease of putative vasospastic origin
that causes massive hemorrhages. Although once considered rare, awareness of this
disease has resulted in increased reports in the pathology and radiology literature.
Despite this, uncertainties concerning pathologic and radiologic correlations, the
course of this disease, and aspects of its prognosis exist. This article addresses
these issues.
Thirteen radiologic reports of segmental arterial mediolysis are analyzed, and slides
of 25 cases of segmental arterial mediolysis are searched for lesions analogous to
the radiologic findings.
Six angiographic presentations are identified: (a) arterial dilatation, (b) single
aneurysm, (c) multiple aneurysms, (d) dissecting hematomas, (e) arterial stenosis,
and (f) arterial occlusions. Pathologic correlations reveal that lytic loss of medial
muscle causes arterial dilatation, dilated arterial gaps form aneurysms, dissections
develop at arterial-medial gap junctions or from reparative granulation tissue and
reparative alterations, and thrombi cause stenosis and occlusions. The most common
radiologic findings at onset are aneurysms, arterial dilatation, and occlusions, while
dissections and stenotic lesions often are delayed. These images correlate with the
histologic evolution of segmental arterial mediolysis.
Segmental arterial mediolysis is an acute limited disease. Sequelae recognized radiologically
include aneurysms, dissecting hematomas, arterial stenosis, and occlusions. Generally,
these persist, become smaller, or resolve, but symptomatic dissections with delayed
onset occur. Sequelae of subclinical forms of segmental arterial mediolysis may cause
isolated idiopathic aneurysms or may evolve into arterial lesions indistinguishable
from fibromuscular dysplasia.