• View shows the aorta and common iliac arteries opened
• The aneurysmal cavity is almost filled with an unorganized
thrombus (white arrow) with a central channel of blood flow
having the same diameter as the adjoining intact aorta.
• Note that the arteriosclerotic intima lining the upper edge of the opened aneurysm (white asterisk) has been artefactually split from the media (blue arrow).
•Severe arteriosclerosis a major factor.
•20% familial incidence indicates a genetic defect in
connective tissue component. Mutation of gene encoding
type III procollagen implicated.
•Syphilis and other bacterial infections.
•Cystic medial necrosis.
•Arteriosclerosis causes gradual destruction of the
media with focal weakening of the wall.
•The intraluminal pressure is proportional to the
radius (LaPlace^s Law). An incremental increase in
pressure causes an increased pressure on the inner
surface of the evolving aneurysm with an incremental
increase in the radius, establishing a vicious cycle.
•Familial cases indicate the importance of genetic
defects in connective tissues making the aorta
susceptible to the formation of aneurysms due to
•More common in men.
•Other complications of arteriosclerosis exist in
majority of cases: ischemic heart disease, cerebrovascular disease,
ischemic bowel disease, peripheral vascular disease.
•75 % occur in the abdominal aorta, and are easier to repair than thoracic or thoracicoabdominal lesions
•Asymptomatic until discovered on routine physical
or imaging examinations, or as a cause of back pain.
•Patients may complain of pain and an associated
leaking sensation, a sign of imminent rupture.
•Virtual inevitable rupture with increasing distension
of an aneurysm (LaPlace^s Law) calls for careful
monitoring in cases being followed conservatively.
|General Gross Description|
•Fusiform dilatation of a severely arteriosclerotic
aorta with sharp superior and inferior margins.
•Typically involves the abdominal aorta from just
below the ostia of the renal arteries to the
bifurcation of the aorta.
•Larger aneurysms, >7-8 cm in transverse diameter,
contain a thick old laminated thrombus reducing the patent aneurysmal lumen to a diameter close to
that of the lumen in the adjoining intact aorta.
•Aneurysmal thrombus does not organize due to the
paucity of functioning vasa vasorum in the fibrotic
thinned out aneurysmal wall.
|General Micro Description|
•Wall of aneurysm made up of a barely identifiable
media, which is replaced by a fibrotic
arteriosclerotic lesion with focal aggregates of
•Adventitia is fibrotic with chronic inflammation and
merges with media.
• Cotran RS,
Kumar V, Robbins SL. Robbins Pathologic Basis of Disease. 5th edition. Philadelphia, W.B. Saunders, 1994, pp. 500-501.
• Harrison^s Principles of Internal Medicine, 13th
Edition. New York, McGraw-Hill, 1994, pp. 1131-1133.