CLINICAL STUDY

Segmental Arterial Mediolysis: Clinical and Imaging

Features at Presentation and during Follow-up

Sanjeeva P. Kalva, MD, Bhanusupriya Somarouthu, MD,Michael R. Jaff, DO, and Stephan Wicky, MD

ABSTRACT

Purpose: To review clinical and imaging features at presentation and during follow-up of patients with a suspected diagnosis ofsegmental arterial mediolysis (SAM).

Materials and Methods: All cases of SAM diagnosed at a single institution from 2000 to 2010 were included. Diagnosis was basedon characteristic radiologic features in the absence of other plausible diagnoses. Medical records were reviewed for demographics,presenting symptoms, and laboratory and imaging findings at presentation and during follow-up.

Results: Fourteen patients (nine men; mean age, 53 y � 15) were diagnosed with SAM. Initial presentation included abdominal orflank pain (n � 8) and chest pain, headache, stroke, or suprapubic fullness (n � 1 each). Two patients were asymptomatic.Inflammatory markers were negative in all cases. Imaging at presentation revealed involvement of celiac (n � 7), common hepatic(n � 3), splenic (n � 2), superior mesenteric (n � 5), renal (n � 5), and iliac (n � 2) arteries and the abdominal aorta (n � 1). Imagingdemonstrated arterial dissections (n � 10), fusiform aneurysms (n � 6), arterial wall thickening (n � 2), and artery occlusion (n �1). Clinical follow-up was available in 13 patients (median, 25 mo). Symptoms improved (n � 4), resolved (n � 3), or remained stable(n � 2), and four patients experienced new symptoms. Follow-up imaging, available in 10 patients at a median of 33 months,demonstrated new dissections, aneurysms, or arterial occlusions in five patients, including carotid artery dissection in three. Imagingfindings remained stable (n � 3), improved (n � 1), or resolved (n � 1).

Conclusions: SAM affects middle-aged and elderly patients. Visceral artery dissections and aneurysms are common. The diseaseprogresses in nearly half the patients. Serial follow-up with computed tomographic angiography and/or magnetic resonanceangiography may be necessary to monitor disease progression.

ABBREVIATIONS

ANCA � antineutrophil cytoplasmic antibodies, FMD � fibromuscular dysplasia, SAM � segmental arterial mediolysis

(civ

ibtiisndnics

Segmental arterial mediolysis (SAM) is an unusual nonin-flammatory, nonatherosclerotic disorder with a predilectionfor the splanchnic arteries (1). The etiology of this diseaseis unknown. Some authors have postulated that it representsa variant or precursor of fibromuscular dysplasia (FMD)(1,2), whereas others suggest that SAM is secondary tovasospasm or injury to the arterial wall from immunecomplexes (3). Since its original description by Slavin et al

From the Departments of Radiology (S.P.K., B.S., S.W.) and Vascular Medi-cine (M.R.J.), Massachusetts General Hospital, GRB-832, 55 Fruit St., Boston,MA 02114. Received March 9, 2011; final revision received June 6, 2011;accepted July 12, 2011. Address correspondence to S.P.K.; E-mail:skalva@partners.org

None of the authors have identified a conflict of interest.

© SIR, 2011

J Vasc Interv Radiol 2011; 22:1380–1387

iDOI: 10.1016/j.jvir.2011.07.001

4) in 1976 as “segmental mediolytic arteritis,” nearly 50ases have been reported in the literature (5). The conditions now known as SAM to differentiate it from inflammatoryasculitis (6).

Current literature on SAM is limited to a series ofndividual case reports (5). The diagnosis has historicallyeen confirmed by histopathologic examination of the ar-eries involved. Despite well recognized characteristic clin-cal and arteriographic patterns in the absence of abnormalnflammatory laboratory findings, there is a lack of consen-us regarding noninvasive diagnostic criteria for the diag-osis of SAM. Similarly, long-term manifestations of thisisease are unknown. A few small studies in a limitedumber of patients demonstrated stability or resolution ofmaging findings in the short term (7). In addition, a benignlinical course is often reported; however, there are nopecific follow-up imaging guidelines.

In the present study, we reviewed the clinical and

maging findings at presentation and during follow-up in

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Volume 22 � Number 10 � October � 2011 1381

patients diagnosed with SAM at a single institution. Thediagnosis of SAM was based on consensus guidelines de-veloped by a multidisciplinary group of vascular physiciansin our institution (Table 1).

MATERIALS AND METHODS

This retrospective study was approved by the institutionalreview board and was compliant with the Health InsurancePortability and Accountability Act. The review boardwaived the requirement to obtain informed consent fromthe study subjects for inclusion in this study.

Study DesignElectronic medical records were searched for patients whowere diagnosed with SAM during the period from January2000 to December 2010. All patients who met the guide-lines developed by our multidisciplinary vascular group(Table 1) were included in this study. Demographics, pre-senting symptoms, and initial and follow-up laboratory andimaging findings were recorded in a database.

PatientsThirty-six patients were diagnosed with SAM during thestudy period; however, only 14 patients met the criteriadeveloped by our physicians (Table 1) and were includedin the study. The remaining 22 patients were excludedbecause they did not have laboratory results to exclude thepresence of other forms of vasculitis. There were nine menand five women, with a mean age of 53 years (range, 29–97y; median, 53 y). Ten patients (71%) were receiving anti-hypertensive medications at the time of diagnosis. Onepatient had diabetes mellitus. A history of smoking wasnoted in three patients; alcoholism in seven, migraine head-aches in three, hypercholesterolemia in five, peripheral ar-tery disease in one, and coronary artery disease in one.

ImagingThirteen patients underwent visceral computed tomo-graphic (CT) angiography performed on a multidetector CTscanner (GE Medical Systems, Milwaukee, Wisconsin)

Table 1. Institutional Guidelines for Diagnosis of Segmental A

Criteria

Clinical Absence of congenital predisposition fo

more plausible diagnosis such as fibr

Acute Abdominal or flank pain, back pain, che

Chronic Abdominal pain, hypertension, hematu

Imaging Dissection/fusiform aneurysm/occlusion

arteries with or without organ infarct

Laboratory Absence of inflammatory markers such

antibodies; normal complement level

with dedicated institution-approved CT angiography proto- p

ols. The salient features of the protocol include CT imag-ng during the arterial and venous phases of the abdomennd pelvis with 100–120 mL of iodinated contrast materialnd 1.25-mm slice thickness, and three-dimensional angio-raphic reconstruction of the imaging data. The imagingata were reviewed by board-certified radiologists withore than 10 years of experience in the interpretation of CT

ngiography studies. In addition to CT angiography, oneatient had magnetic resonance (MR) angiography of theesenteric and renal arteries. Two patients had catheter

ngiography of the abdominal aorta and mesenteric andenal arteries in addition to CT angiography. One patientad MR angiography of the abdominal aorta and mesentericnd renal arteries. Additional studies such as CT angiogra-hy and MR angiography of the neck and brain wereeviewed when available to assess for arterial pathologicrocesses such as dissection, aneurysm, occlusion, or ste-osis, and any other nonvascular findings such as hemor-hage or infarction. On the follow-up imaging studies,hanges in arterial pathologic findings and new vascularnd nonvascular findings were recorded.

ollow-uplectronic medical records were reviewed for changes inymptoms or the development of new symptoms. On fol-ow-up, symptoms were categorized as stable (if symptomsersisted with no significant change), improved (symptomsecreased but not completely resolved), resolved (all symp-oms resolved), or progressed (presenting symptoms wors-ned), and the development of new symptoms was alsooted. Similarly, follow-up imaging findings were catego-ized as stable, improved, resolved, or progressed, and theevelopment of new imaging findings was noted.

ESULTS

linical Presentationbdominal pain was the most common clinical presentation

Table 2). Seven of the 14 patients (50%) presented withbdominal pain, four with an acute abdomen, and three withhronic abdominal pain. Other symptoms included flank

l Mediolysis

Presentation

ections (eg, Ehlers–Danlos, Marfan, Loeys–Dietz), absence of

ular dysplasia, collagen vascular disorder, or arteritis

n, acute hypertension, hypotension, hematuria or stroke

symptoms

ed appearance/wall thickening of the mesenteric or renal

associated contiguous aortic dissection or atherosclerosis

tinuclear antibodies and antineutrophil cytoplasmic

rteria

r diss

omusc

st pai

ria, no

/bead

ion; no

as an

s

ain, chest pain, headache, stroke with hemiparesis, and

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1382 � Segmental Arterial Mediolysis: Clinical and Imaging Features Kalva et al � JVIR

suprapubic fullness in one patient each. Two patients wereasymptomatic: the imaging findings characteristic of SAMwere identified on imaging performed for follow-up ofrenal cell cancer in one patient and cold-induced digitalischemia in the other. None had a family history or clinicalsigns to suggest an alternate diagnosis (eg, Marfan syn-drome, Ehlers–Danlos syndromes, FMD).

Laboratory FindingsAntinuclear antibody assays were performed in all patients.Findings of the screening study were negative in five pa-tients and slightly positive at 1:40 in eight. Study resultswere positive at 1:640 in one patient. In this patient, sub-

Table 2. Clinical and Imaging Findings at Presentation and Fo

Pt. No. Age (y)/Sex Clinical Prese

1 73/M Suprapubic fullness

2 54/F Left flank pain

3 48/M Acute abdominal pain

4 63/M Chronic abdominal pain

5 40/M Acute abdominal pain

6 87/M Follow-up of cold-induce

7 41/F Acute abdominal pain

8 55/F Follow-up of renal cell c

9 29/M Acute chest pain

10 51/M Chronic abdominal pain

11 62/M Left upper-extremity we

status changes

12 44/M Headache

13 58/F Chronic abdominal pain

14 41/F Acute abdominal pain

Note.—ANA � antinuclear antibody, ANCA � antineutrophil cstranded DNA, EDS � Ehlers–Danlos syndrome, ESR � erythmesenteric artery.

sequent anti-Ro, anti-La, anticentromere, and antineutrophil a

ytoplasmic antibodies (ANCA) were negative. Three pa-ients had negative assay findings for anti–double-strandedNA antibodies. Negative ANCA was noted in nine pa-

ients. Total hemolytic complement levels were normal inix patients and low in one. C-reactive protein was tested inight patients and was found to be increased in four, rang-ng from 20 to 98 mg/L with a mean of 55 mg/L � 37.rythrocyte sedimentation rate was normal in one patient inhom this was assayed. Genetic tests for Ehlers–Danlos

yndrome were negative in two patients.

maging Findingsngiography (CT angiography/MR angiography/catheter

p

n Imaging Findings

Fusiform aneurysm of the SMA,

bilateral iliac arteries

Left renal artery dissection with infarct

in left kidney

Left renal artery dissection with infarct

in left kidney

Thrombotic occlusion of celiac and

hepatic arteries

Left renal artery dissection with infarct

in left kidney

tal ischemia Dissection of SMA, aneurysm in celiac,

bilateral renal, and right iliac arteries

Dissection of celiac and splenic

arteries

ma Celiac dissection

Dissection in SMA, aneurysm in celiac

artery and ascending aorta

Dissection of SMA

, mental Celiac dissection, right renal

aneurysm, bilateral renal infarcts

Bilateral renal artery aneurysm, arterial

wall thickening of hepatic artery

Arterial wall thickening of SMA

Dissection of celiac and hepatic

arteries and SMA

smic antibodies, CRP � c-reactive protein, dsDNA � double-sedimentation rate, NA � not applicable, SMA � superior

llow-u

ntatio

d digi

arcino

akness

ytoplarocyte

ngiography) at presentation demonstrated involvement of

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Volume 22 � Number 10 � October � 2011 1383

the celiac artery in seven patients (Fig 1), common hepaticartery in three, splenic artery in two, superior mesentericartery in five (Fig 2), renal artery in five, iliac artery intwo, and abdominal aorta in one. Vascular findings in-cluded arterial dissections (n � 10; Figs 1–2), fusiformaneurysms (n � 6), arterial wall thickening (n � 2), andartery occlusion (n � 1; Table 2). Nonvascular findingsincluded renal infarcts in four patients.

Follow-upClinical follow-up was available in 13 patients (93%).Follow-up durations ranged from 4 to 112 months with amean of 38 months � 36 (median, 25 mo). No patient died

Laboratory Findings Medication

ANA negative, negative anti-Ro,

anti-La, anti-Sm, anti-Jo,

ANCA; normal C3, low C4

Antihypertensives

ANA negative, negative ANCA;

normal C3, C4; CRP elevated;

negative for COL3A1 gene

Anticoagulation

ANA negative, negative anti-

dsDNA, anti-Ro, anti-La

Antihypertensives

ANA negative; normal C3, low

C4; CRP normal

Antihypertensives, steroids

ANA positive; negative anti-Ro,

anti-La, ANCA; normal C3, C4;

CRP elevated

Antihypertensives

ANA negative; negative ANCA;

low C3, C4

Steroids

ANA negative; negative ANCA;

normal C3, C4; CRP elevated

Antihypertensives

ANA negative; negative ANCA Antihypertensives

ANA negative; CRP normal None

ANA negative; negative ANCA;

CRP normal

Antihypertensives,

anticoagulation

ANA negative; genetic tests

negative for EDS

Antihypertensives,

anticoagulation

ANA negative; negative anti-

dsDNA, ANCA

Antihypertensives

ANA negative; normal CRP,

ESR

Anticoagulation

ANA negative; normal C3, C4;

CRP elevated

Antihypertensives

uring follow-up. Four patients who had dissections on b

maging studies received systemic anticoagulation witharfarin (n � 2) or low molecular weight heparin (n � 2).ymptoms improved in four of 13 patients (31%), resolved

n three (23%), and progressed in one (8%), and newymptoms developed in three (23%; Table 2). All threeatients (23%) who developed new symptoms experiencedcute onset of headaches and were found to have internalarotid artery dissection. One of the three patients alsoeveloped a vertebral artery dissection. Two patients whoere incidentally diagnosed with SAM remained symptom-

ree during follow-up. Two patients (16%) received sys-emic corticosteroids, one of whom had presented withhronic abdominal pain. The symptoms initially resolved

Follow-up

Clinical Imaging

ptoms improved New left renal aneurysm; others

stable

symptoms,

eadache

New left internal carotid dissection

and vertebral artery stenosis

ptoms improved Stable

urrent abdominal pain Recanalization of celiac and

hepatic arteries

ptoms improved NA

ained asymptomatic NA

ptoms resolved Progressed to occlusion of the

celiac, hepatic, and splenic

arteries with splenic infarction

ained asymptomatic Resolution of the celiac dissection

ptoms improved NA

symptoms,

eadache

Resolution of SMA dissection; new

left internal carotid and vertebral

artery dissections

symptoms,

eadache

Stable abdominal findings; new

bilateral internal carotid

dissection

ptoms resolved Stable

NA NA

ptoms resolved Stable

Sym

New

h

Sym

Rec

Sym

Rem

Sym

Rem

Sym

New

h

New

h

Sym

Sym

ut recurred with increased severity and at a different

t

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1384 � Segmental Arterial Mediolysis: Clinical and Imaging Features Kalva et al � JVIR

location. In the second patient, the symptoms resolved.Laboratory studies during follow-up were available in fourpatients. Findings of antinuclear antibody and ANCA as-says remained negative in these patients.

Follow-up CT angiography was available in 10 patients(71%) after a median of 33 months (range, 4–112 mo). Thenumber of follow-up imaging studies ranged from one tofive, with an average of three per patient. Vascular imagingfindings remained stable in three of these 10 patients (30%),improved in one (10%), and resolved in one (10%). Pro-gression of the disease occurred in one patient (10%); inthis patient, dissection of the celiac, hepatic, and splenicarteries progressed to arterial occlusion with splenic infarc-tion (Fig 1). New imaging findings were seen in fourpatients (40%; Table 2). New arterial dissections involvedhe internal carotid artery in three patients (Fig 2) and the

vertebral artery in one. One patient developed a new leftrenal artery aneurysm.

DISCUSSION

The incidence of SAM is unknown but is probably under-estimated (7). The disease affects middle-aged and elderlypatients with no male or female predilection. The splanch-nic vessels are most commonly involved. However, in-volvement of the carotid, renal, intracranial, and iliac arter-ies has been reported (5). The pattern of vascularinvolvement varies with age; cerebral vasculature is more

Figure 1. Images from a 41-year-old woman who presented witceliac artery. One week after presentation, the patient developedof the false lumen of the celiac artery. The dissection flap (arrothe splenic artery with a splenic infarct (small arrows). Five weethis time shows resolution of celiac dissection (arrow) with warrows) is smaller at this time. Six months later, she was asymceliac artery.

commonly involved in young patients (8), whereas the w

oronary arteries are commonly involved in neonates andreterm infants (9–11). Pathologically, there is vacuolaregeneration of the smooth muscle in the outer media thatesults in gaps in the arterial wall, leading to aneurysms andissections (6,7). There is little inflammatory response ofhe involved regions. Reparative fibrosis leads to vesselemodeling and restoration of a smooth arterial wall12,13). Some authors propose that SAM represents a vari-nt or precursor of FMD (14). Unlike SAM, FMD prefer-ntially involves young female subjects and results in dif-use disorganization of the media with disruption andeplacement of the smooth muscle cells by collagen in theid- and distal arterial segments (15). Stenotic lesions are

ommon, but aneurysms and dissections are less commonn FMD (15,16). Other differential considerations for SAMnclude polyarteritis nodosa, Takayasu arteritis, Behçet dis-ase, allergic granulomatous angiitis, and collagen disor-ers (eg, Ehlers–Danlos syndrome, Loeys–Dietz syndrome,eurofibromatosis) (16). The pathologic findings of theseisorders are characteristic, as are patient characteristicsnd laboratory abnormalities (16). Dissections and aneu-ysms are common in Marfan and Ehlers–Danlos syn-romes, as are aneurysms in Loeys–Dietz syndrome, butnvolvement of the splanchnic vasculature is less common.eurofibromatosis causes long-segment stenoses and aneu-

ysms, but dissections are uncommon (16).In a recent review (5) that pooled data from all reported

ases of SAM from 1976 to 2007 (N � 47), abdominal pain

minal pain. (a) CT angiography shows dissection (arrow) of thesing abdominal pain. (b) CT angiography shows increased size

learly visible. (c) Superiorly, there is occlusion (large arrow) ofr presentation, her symptoms improved. (d) CT angiography atg of the lumen of the celiac artery. The splenic infarct (smalltic. (e) Repeat CT angiography shows occlusion (arrow) of the

h abdoincrea

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as the most common presenting symptom, reported in

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Volume 22 � Number 10 � October � 2011 1385

62%, followed by shock in 32%, abdominal distension in13%, hematochezia in 11%, and stroke in 6%. Nine percentof the patients were asymptomatic. In comparison, 50% ofthe patients in this series (n � 7) presented with abdominal

Figure 2. Images from a 51-year-old man who presentedangiography data shows dissection of the superior mesenterlumen (large arrow). The patient’s symptoms improved inresolution of the dissection of the superior mesenteric arterypresented with headache. (c) CT angiography of the neck swas no neurologic deficit. (d) CT angiography 4 months la(arrow).

pain, with other symptoms such as headache, stroke, chest y

ain, flank pain, or suprapubic fullness occurring at lowerrequency (7% each). Two patients (14%) were asymptom-tic in the present study cohort. The mean age at presenta-ion was 53 years in the present study, compared with 58

abdominal pain. (a) Reformatted sagittal image from CTry with a small true lumen (small arrow) and a larger falseths. (b) Subsequent CT angiography shows near-completeestoration of the lumen (arrow). Four years later, the patientdissection (arrow) of the left internal carotid artery. Thereows near-complete resolution of carotid artery dissection

withic arte

7 monwith rhowster sh

ears in the pooled data (5). Multiple vessels were involved

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1386 � Segmental Arterial Mediolysis: Clinical and Imaging Features Kalva et al � JVIR

in 56% of our patients (n � 8) at presentation, but pro-gressed to 70% (n � 10), compared with 47% reported inthe literature (17,18). This suggests that SAM usually in-volves multiple vessels during the course of the disease. Inthe present study, the splanchnic arteries were involved in77% of cases (n � 11), renal arteries in 50% (n � 7), iliacrteries in 14% (n � 2), and extracranial cerebral arteries in1% (n � 3). In comparison, pooled data (5) includednvolvement of the splanchnic arteries in 76%, renal arteriesn 7%, iliac arteries in 2.3%, extracranial cerebral arteries in.3%, and intracranial arteries in 4.5%. The difference inascular involvement in the present group may be related tohe sample size, varying presentation, and age differencesn the study population. The imaging findings in the presenttudy were similar to those previously reported in theiterature (5). Disease progression was variable in our co-ort, with 23% of our patients (three of 13) developing newymptoms, but imaging demonstrated new dissections, an-urysms, and artery occlusions in other vascular territoriesn four of 10 patients (40%) during follow-up. However, inne study (7) in which follow-up data were reported on fouratients, the imaging findings resolved or stabilized in allatients, with no disease progression. Resolution of initialesions with late onset dissections in other vascular territo-ies has been reported (19). This suggests that asymptom-tic disease progression may be common in SAM. Simi-arly, the overall prognosis is highly variable, depending onhe initial presentation. Pooled data (5) revealed a 40%verall mortality rate, with nearly 86% of these patientsying before the initiation of invasive treatment. However,n the present series, there were no deaths during follow-up.

There are no specific guidelines for the management ofAM. Patients with shock and intraabdominal hemorrhagere often treated with emergent surgery (5), with variableutcomes. Endovascular therapies used as primary manage-ent of organ ischemia have been reported (5). Other

tudies have suggested that the benign course of the diseaseequires no therapy (7). Given that the arterial wall is proneo dissection and aneurysm formation from medial lysis,ntraarterial catheter manipulation and balloon dilation mayesult in progression or development of new arterial dissec-ions. Therefore, invasive management may be reserved foratients in hemodynamically unstable condition and thoseith significant end-organ ischemia (20–23). In the present

tudy, none of the patients received any endovascular orpen surgical therapy. The utility of corticosteroids in theanagement of this disease is questionable, given the ab-

ence of inflammation on pathologic studies. Active man-gement of hypertension may be beneficial (24). The role ofystemic anticoagulation remains unclear. Although antico-gulation or antiplatelet therapy are commonly used inome cases of arterial dissection, the benefits of their usere not certain. Four patients in the present series werereated with systemic anticoagulation, but the duration ofherapy, if chosen, is unknown.

The present study has several limitations. None of our

atients had pathologic evaluation of the arteries involved,

nd the diagnosis was made solely on the basis of clinicalnd imaging findings with the absence of laboratory abnor-alities or alternative diagnoses that were more plausible

han SAM. Our diagnostic criteria were based on reportsrom the literature, and it is unethical to subject patients tonvasive procedures solely to obtain pathologic evaluationithout a proper indication. However, further studies are

equired to validate our diagnostic criteria. The presenttudy is retrospective and included only patients who metur diagnostic criteria. Some patients with imaging featureslassic for SAM were excluded as a result of a lack oforresponding laboratory findings. A prospective studyould be ideal, but there may not be sufficient numbers of

ases to carry it out. Unfortunately, only 70% of patients inur cohort (10 of 14) had follow-up imaging. Thirty percentf the cohort may have had asymptomatic progression orevelopment of new arterial involvement, but this remainsnconfirmed.

With increasing awareness of SAM, and recommenda-ions for conservative management, pathologic tissue diag-oses will be uncommon (7). The diagnosis will likely restn clinical and imaging findings and the absence of labo-atory abnormalities or emergence of an alternate diagnosis.rogression of the disease varies, so follow-up with CTngiography or MR angiography may be recommended20,25). The duration and timing of imaging follow-up areot known. We suggest imaging follow-up at least once perear. Primary therapy for SAM is supportive, consisting ofain management, antihypertensive therapy, and, at a min-mum, antiplatelet therapy. The use of systemic anticoagu-ation is likely reserved for patients with arterial dissec-ions, but the duration of anticoagulation is uncertain. Aulticenter observation registry may offer further insights

nto the clinical and imaging characteristics of SAM, andllow for more specific diagnostic, therapeutic, and fol-ow-up recommendations.

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