Pathologic Quiz Case: Leg Claudication in Young Patients

Two young female patients presented with a several-month history of progressive unilateral leg claudication. Both were in excellent health aside from this complaint. They had been athletic in the past, but recent activities were severely reduced due to poor exercise tolerance, pain with walking, and claudication. Neither patient had risk factors for vascular disease and neither was a smoker.The first patient had popliteal artery stenosis demonstrated by ultrasound and angiography. At surgery, a “cyst” involving the arterial wall was evacuated and unroofed. It contained “jelly”-like contents that on microscopic examination were on the outer part of the artery wall; the contents were bluish by routine hematoxylin, phloxine, and saffron and Movat pentachrome stains (Figure 1; M indicates media; A, adventitial material). No vasculitis was noted. Since evacuation of the mass the patient has done well with no claudication.The second patient also had a popliteal mass with occlusion of the vessel demonstrated by angiography. Since the vessel was occluded, replacement of the involved arterial segment with bypass grafting was performed. The excised segment was dilated and contained mural thrombus (Figure 2; T indicates thrombus). Microscopy of the vessel wall showed medial disruption, fragmentation of the internal elastic lamina, and transmural fibrosis (Figure 3, Movat pentachrome stain; I indicates intima; M, media; T, thrombus; and arrows, fragmented internal elastic lamina). The lumen had organizing thrombus. No vasculitis was noted. The patient has done well since the surgery with no claudication.Claudication in young patients is not a common problem that the anatomic pathologist encounters in surgical or autopsy specimens. The development of claudication or ischemia of a leg in an otherwise healthy young patient is a dramatic clinical event.The differential diagnosis in these cases includes such well-known entities as thrombus, embolic or in situ, from disorders such as anti–phospholipid antibody syndrome. Vasculitis is also a well-known entity, with Buerger disease being the disorder that one usually thinks of in patients, usually young men, who use tobacco and have limb claudication. Other entities that are less well-known to pathologists include arterial damage from popliteal artery compression syndrome and cystic adventitial disease.Popliteal artery compression syndrome is a common cause of claudication in adults younger than 40 years. If untreated, the disease may be aggressive and lead to vascular occlusion and potential limb loss. Four types of entrapment are recognized.1–3 In several of these, the popliteal artery is located medially and is entrapped by the medial head of the gastrocnemius muscle in the popliteal fossa. Other types involve entrapment of the artery by fibrous popliteal fossa bands or accessory slips of muscle. Athletes with hypertrophied muscles may be prone to develop this problem if they have the underlying popliteal arterial anatomy. The pathology of the artery is similar to any other type of extrinsic recurrent arterial compression with damage. Levien3 divided the arterial damage into 3 stages of progressive damage. The earliest has adventitial fibrosis and neovascularization, and the most advanced has transmural vascular fibrosis, often with aneurysm and thrombosis. The second patient described herein had aneurysmal changes with advanced degenerative disease. The media was thin with internal elastic lamina fragmentation and there was luminal thrombosis.It has been stressed that advanced lesions, in which the artery is occluded and aneurysmal, require bypass grafting rather than thrombus evacuation and vascular patching.2 The damage in advanced lesions is not reversible. Surgery for less damaged vessels may release the compression and lyse the fibrous bands responsible for the condition.Cystic adventitial disease is a rare cause of limb ischemia in young patients, but it has distinctive operative and pathologic findings of which the pathologist should be aware. This disorder commonly involves the popliteal artery, but has also been described in the arteries around the ankle, the elbow, and the wrist, as well as the saphenous vein. It is of uncertain etiology, with most investigators favoring either a repetitive trauma or an embryological cause.4,5The disorder presents with sudden claudication in young patients, in the absence of other vascular disease. The pathology findings consist of a cyst of gelatinous contents between the media and adventitia causing luminal compression. The operative findings are distinctive, namely, a localized mass with jellylike contents under pressure when incised. The mucoid substance is a proteohyaluronic acid–like material. The cyst has no distinct lining and resembles a ganglion.5 Commonly, the cyst contents may be received separate from the arterial wall biopsy. Some (those who believe in an embryological explanation) think the cyst derives from joint capsule mesenchymal tissue that inadvertently gets entrapped in the arterial wall during embryonic development.4 Simple cyst aspiration or evacuation of the contents may treat this disorder. Arterial reconstruction or arterial bypass is recommended if the artery is occluded.5In evaluating cases of vascular disorders, one must have an organized approach. Elastic stain is invaluable to aid one in determining whether the disorder involves an artery, a vein, or both. One must also be aware of the specific disorders that affect the vessel in the location involved.Cystic adventitial disease and popliteal artery degenerative changes from entrapment are both disorders that affect the popliteal artery in young patients. The pathologist may encounter these disorders in frozen sections, excised arterial segments from bypass surgery, or in amputated limbs. Awareness of the histopathology of these entities is not widespread, but is necessary to recognize the disorders.

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