Multiple hereditary exostoses as a rarenonatherosclerotic etiology of chronic lowerextremity ischemiaImtiaz Khan, BS, Charles A. West Jr., MD, Guillermo P. Sangster, MD, Maureen Heldmann, MD,Linda Doucet, RN, and Margaret Olmedo, MD, Shreveport, La

Nonatherosclerotic etiologies of arterial insufficiency are uncommon but important causes of chronic lower extremityischemia. We report a patient with multiple hereditary exostoses (MHE) presenting with lifestyle-limiting lowerextremity claudication and popliteal artery occlusion secondary to a large osteochondroma. The presence of MHE withassociated osteochondroma resulting in arterial occlusion is a rare condition. Management strategies for treating largeosteochondromas adjacent to or with vessel involvement in asymptomatic patients remain undefined. (J Vasc Surg 2010;

51:1003-5.)

Osteochondromas arising from the lower extremitiesthat result in arterial ischemia are unusual and rarely em-phasized as a nonatherosclerotic cause of artery disease.1

These lesions are the most common benign bone tumorsaccounting for up to 40% of all benign bone tumors.2,3 Themajority of these occur as solitary tumors (90%), or lesscommonly may occur as multiple tumors in the form ofmultiple osteocartilaginous exostoses or multiple heredi-tary exostoses (MHE).3-5

Vascular complications in association with osteochon-dromas are well described and have been reported in over100 cases in the literature.3,4,6-9 These tumors affect longbones resulting in pseudoaneurysm, arterial occlusions, orstenosis, phlebitis, and venous thrombosis with the formerbeing most common.2,6-8 Approximately 30 cases resultingfrom arterial ischemia have been reported as a result ofcompression or occlusion of the lower extremity arteries.6

Lesions may involve any bone but most frequently occur inthe distal femur around the knee joint predisposing thepopliteal artery to injury.2,4

This report describes an unusual case of chronic popli-teal artery occlusion secondary to an osteochondroma orig-inating from the tibia in a female patient with MHE.

CASE REPORT

A 52-year-old physically active female presented with a 2-yearhistory of progressive lifestyle-limiting right lower extremity clau-dication. The patient had a history significant for mild hyperten-sion, remote tobacco usage only, and carried the diagnosis of

From the Department of Surgery, Division of Vascular Surgery, LouisianaState University Health Science Center.

Competition of interest: none.Reprint requests: Dr Charles Adger West Jr., MD, Henry Ford Hospital,

Department of Surgery, Division of Vascular Surgery, 2799 West GrandBlvd, Suite K-8, Detroit, MI 48202 (e-mail: cwest5@hfhs.org).

The editors and reviewers of this article have no relevant financial relationshipsto disclose per the JVS policy that requires reviewers to decline review of anymanuscript for which they may have a competition of interest.

0741-5214/$36.00Copyright © 2010 by the Society for Vascular Surgery.

doi:10.1016/j.jvs.2009.10.123

MHE since childhood; additionally, family history revealed a his-tory of MHE in her father and brother. On physical examination,a protuberant bony deformity was noted on inspection and palpa-tion over the medial aspect of the right lower leg at the level of thetibial tuberosity. Femoral pulses were normal in the right lowerextremity; a popliteal pulse was absent, and pedal pulses were weakbut present. A normal pulse examination was present in the leftlower extremity. The ABIs were 0.9 and 1.18, respectively. Arterialduplex scan of the lower extremities demonstrated high-resistancewaveform in the right proximal popliteal artery with evidence ofarterial occlusion. Lower extremity radiographs were diagnosticdemonstrating a large osteochondroma occupying the poplitealfossa. The patient was started on antiplatelet therapy and at-tempted a regimen of daily walking but failed to achieve satisfac-tory results after 6 weeks. The patient was subsequently evaluatedfor arterial reconstruction. A computed tomography (CT) angiog-raphy (Fig) demonstrates displacement and occlusion of the pop-liteal artery with evidence of the femoral and tibial bone tumors.Arterial reconstruction was planned after conventional digital sub-traction angiography (DSA) was performed revealing normalaorto-iliofemoral anatomy with an isolated right below-knee pop-liteal artery occlusion with collateralization of the proximal poste-rior tibial artery. Surgical treatment included a right above-kneepopliteal artery to posterior tibial artery bypass though medialsuprageniculate and infrageniculate incisions with reversed greatsaphenous vein. The graft was tunneled slightly medial and inferi-orly around the large exostosis. Bony spikes were not appreciatedon the surface of the lesion and there was no evidence of a falseaneurysm involving the popliteal artery. The postoperative conva-lescences were uneventful. At follow-up after 5 months, the duplexultrasound scan surveillance was normal, ABIs on the right were1.16, and she remains free of claudication at 1 year.

DISCUSSION

Multiple hereditary exostoses are a heterogenous skel-etal disorder with prevalence estimated at 1 in 50,000.5

The condition was first described by Boyer in 1814 withone of the earliest reports being a multifamily case series

from 1845.10 MHE is a skeletal disorder that involves the

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JOURNAL OF VASCULAR SURGERYApril 20101004 Khan et al

epiphyseal growth plates characterized by the presence ofmultiple cartilage-capped bony exostoses or osteochondro-mas.5,11 The pathobiology is believed to begin with dyspla-

Fig. Contrast-enhanced multidetector computed tomographyscan of the knee. A, 3D volume rendered demonstrates a distalfemoral and a proximal tibial enchondroma (arrows). The tibialenchondroma produces displacement of the popliteal vessels. Thepopliteal artery is occluded (arrowhead) with delineation of collat-eral circulation in the proximal leg. B, Sagittal maximum-intensityprojection reconstruction shows a soft tissue abnormality aroundthe osteochondroma representing inflammatory tissue (arrow-heads). The popliteal occlusion is identified (arrow).

sia of the peripheral aspect of the growth plate. MHE often

presents with limb length discrepancies, osteoarthritis, andlimited range of motion.11 MHE most commonly affectsjoints of the upper and lower limbs, in particular the distalfemur, tibia, and humerus; however, it can be found any-where in the skeletal structure including pubis, scapula, andvertebrae.5 It is passed on in an autosomal dominant patternwith nearly complete penetrance, however, up to 40% of casesrepresent new mutations.11,12 The predominant genetic basisof MHE is through mutations in the EXT gene family includ-ing EXT1, EXT2, and EXT3, and prevalence is approximately1 in 50,000.5,11,12 The potential for osteochondromas totransform into malignant lesions is reported to carry a riskranging from 0.6% to 2.8%.12

An array of vascular complications has been reported inassociation with osteochondromas most commonly affect-ing young male patients with a ratio of 4:1.3,4 Theseinclude false aneurysms, arterial compression, arterialthrombosis, arterial trauma, and venous thrombosis lead-ing to claudication, acute limb ischemia, and phlebitis.Vasseur and Fabre4 reviewed 97 cases of vascular compro-mise related to osteochondromas and reported 6 new casesin their series. The predominate location for these lesionswas in the lower metaphysis of the distal femur (83%).Formation of a false aneurysm was the most frequentvascular complication (56%) followed by vascular compres-sion (16%) and arterial thrombosis (14%). In 2003, An-drikopoulos et al3 reported 11 cases of osteochondromasinvolving the lower extremity arteries requiring surgicaltreatment. Seven patients had popliteal artery involvement,4 of which were occlusions, and only 3 of the 11 patientswere deemed to have hereditary multiple exostosis syn-drome.3

Nonatherosclerotic diseases of the popliteal artery are asignificant cause of arterial insufficiency in primarily youngpatients without traditional risk factors for atheroscleroticvascular disease. These include primarily popliteal arteryentrapment, cystic advential disease, remote trauma, andradiation injury.1,13-15 The presence of an osteochondromaof the distal femur or tibia represent a structural abnormal-ity in regions of the lower extremity where the artery is fixedin position and is vulnerable to injury from adjacent tumorthat ultimately may result in ischemic complications.16

Although vascular complications have been well describedin patients with these bony abnormalities, it has yet to berecognized as a nonatherosclerotic vascular lesion.

Diagnosis begins with plain radiograph imaging of thelower extremities in those with hemodynamic evidence ofarterial insufficiency (ABI � 0.9) who lack traditional car-diovascular risk factors, especially in patients with a historyof MHE or clinical evidence of osteochondromas. A CTscan or magnetic resonance imaging (MRI) scan offersmultidimensional enhanced soft tissue imaging that mayunveil an aneurysm (arterial and venous) or bony compres-sion of neurovascular structures undetected by conven-tional arteriography. An MRI may be useful in evaluatingsymptomatic lesions.2 This modality can determine thick-ness of the cartilage cap and assist in evaluating sarcomatous

degeneration.2,11 Duplex ultrasonography scan with B

JOURNAL OF VASCULAR SURGERYVolume 51, Number 4 Khan et al 1005

mode imaging provides a noninvasive method to measurehemodynamic changes in flow velocity and detect changesin artery displacement or progressive vessel impingement inthose with smaller bony lesions desired to be followedelectively.

In our case, the popliteal artery was occluded behindthe knee, presumably due to chronic extrinsic compression.Treatment with an open surgical bypass using autogenousvein was the preferred method of revascularization. Percu-taneous interventional procedures (ie, stenting and angio-plasty) of the popliteal artery were not considered due tomultiple well-described limitations.17

Excision of these benign bone tumors has been recom-mended in cases in which the offending lesion is painful,continues to enlarge, occurs in the vicinity of a vessel,interferes with the joint, or if there is evidence of fracture ofthe osteochondroma. Surgical removal of osteochondro-mas has been reported previously in the treatment of MHEbut may be associated with recurrence. Other problemsafter surgical treatment include complications of chronicpain and lifestyle debility.11 Also, a genetic predispositionexists for keloid tumor formation in patients with MHEafter surgical excision has been described.18 Excision of theosteochondromas as a treatment adjunct was considered inthis case but was not performed because the tumor wasasymptomatic and the graft was tunneled without technicaldifficulty around the bony mass that was blunt in texture.These factors dissuaded an extensive bone tumor excision.

CONCLUSION

MHE with associated osteochondromas resulting inarterial ischemia is an unusual cause of lower extremityischemia. When osteochondromas are recognized, empha-sis should be placed on the significance of potential vascularcomplications. Arterial reconstruction without bone tumorexcision is feasible; however, surgical treatment of bonydisease in those with asymptomatic osteochondromas war-rants serious consideration to avoid long-term complica-tions in younger patients.

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Submitted Aug 11, 2009; accepted Oct 28, 2009.