Fig. 10.24 ). Aortic lesions share many of the clinical and histologic features of giant cell aortitis. Indeed, the distinction between the two entities is made largely on the basis of a patient’s age; in those older than 50 years of age are said to have giant cell aortitis, and lesions that occur in those younger than 50 years of age are designated Takayasu aortitis. Although historically associated with Japanese ethnicity and certain HLA haplotypes, Takayasu aortitis has a global distribution. An autoimmune etiology is likely.
Fig. 10.23 Temporal(giantcell)arteritis.(A)Hematoxylin-eosin-stainedsectionofatemporalarteryshowinggiantcellsnearthefragmentedinternalelasticmembrane(arrow), alongwithmedialandadventitialinflammation.(B)Elastictissuestaindemonstratingfocaldestructionoftheinternalelasticmembrane(arrow) andmedialattenuationandscarring.
Fig. 10.24 Takayasuarteritis.(A)Aorticarchangiogramshowingreducedflowofcontrastmaterialintothegreatvesselsandnarrowingofthebrachiocephalic,carotid,andsubclavianarteries(arrows). (B)Cross-sectionsoftherightcarotidarteryfromthepatientshowninAdemonstratingmarkedintimalthickeningandluminalnarrowing.Thewhitecirclescorrespondtotheoriginalvesselwall;theinnercoreoftantissueistheareaofintimalhyperplasia.(C)HistologicappearanceinactiveTakayasuaortitisillustratingdestructionandfibrosisofthearterialmediaassociatedwithmononuclearinfiltratesandgiantcells(arrows).
MORPHOLOGYTakayasu arteritis classically affects the aortic arch and arch vessels; one third of cases also involve the remainder of the aorta and its branches. Occasionally,aorticrootinvolvementcausesdilationandaorticvalveinsufficiency.Pulmonaryarteriesareinvolvedin50%ofpatients,andrenalandcoronaryarteriesalsocanbeaffected.Thetakeoffsofthegreatvesselscanbemarkedlynarrowedandevenobliterated(see
Fig.
10.24AandB ),explainingtheupper-extremityweaknessandfaintcarotidpulses.Thehistologicpicture(see
Fig.10.24C )encompassesaspectrumrangingfromadventitialmononuclearinfiltratesandperivascularcuffingofthevasavasorum,tointensetransmuralmononuclearinflammation,togranulomatousinflammation,repletewithgiantcellsandpatchymedialnecrosis.Theinflammationisassociatedwithirregularthickeningofthevesselwall,intimalhyperplasia,andadventitialfibrosis.
Initial signs and symptoms usually are nonspecific, including fatigue, weight loss, and fever. With progression, vascular signs and symptoms appear and dominate the clinical picture. These include reduced upper-extremity blood pressure and pulse strength; neurologic deficits; and ocular disturbances, including visual field defects, retinal hemorrhages, and total blindness. Distal aorta disease can manifest as leg claudication, and pulmonary artery involvement can cause pulmonary hypertension. Narrowing of the coronary ostia can lead to myocardial infarction, and involvement of the renal arteries causes systemic hypertension in roughly one half of patients. The evolution of the disease is variable. Some cases rapidly progress, while others become quiescent after 1 to 2 years. In the latter scenario, long-term survival, albeit with visual or neurologic deficits, is possible.