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provided by Elsevier - Publisher Connector http://www.kidney-international.org the renal consult & 2009 International Society of Nephrology

Fibromuscular dysplasia C. John Sperati1, Nisha Aggarwal2, Aravind Arepally3 and Mohamed G. Atta1

1Division of Nephrology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA; 2Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, USA and 3Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA

Urinalysis was unrevealing, and proteinuria was estimated CASE PRESENTATION at 0.22 gProtein/gCreatinine on a spot urine sample. A previously healthy 46-year-old African-American man In an attempt to confirm the diagnosis of PAN, the presented to an outside hospital with several weeks of patient underwent testicular ultrasound and mesenteric fever, 20 lb weight loss in the previous month, and left , both of which were normal. Selective renal flank pain. He was hypertensive, urinalysis was notable for angiography was then performed with intravascular the absence of protein, blood, and cellular elements, and ultrasound (IVUS). Angiography demonstrated a tight left the erythrocyte sedimentation rate was minimally mid-renal narrowing (Figure 1) with focal areas of elevated at 23 mm/h. His family history was relevant for infarction throughout the renal parenchyma (Figure 2). uncomplicated in both parents. CT scan with This had mildly worsened since the initial intravenous contrast demonstrated bilateral renal studies, and IVUS demonstrated the presence of a focal infarctions, and serum creatinine rose from 1.2 to flap (Figure 3). In addition, moderate 1.7 mg/dl shortly after admission. Renal angiography improvement since the prior study was seen in both revealed stenoses in both main renal , as well as the stenosis of the right upper pole arterial branch in first- and second-order branches of the vasculature and the associated . to the right upper pole. Aneurysmal dilatations were present in the upper pole branches and at the left hilum. Given the radiographical findings and systemic complaints, the patient was diagnosed with polyarteritis CLINICAL DIAGNOSIS nodosa (PAN) and initiated on steroid therapy. One week Bilateral intimal fibromuscular dysplasia (FMD) of the renal after discharge, the patient complained of chest pain in arteries, complicated by dissection. the setting of persistent flank pain, and his serum creatinine had risen to 2.3 mg/dl. He was readmitted to CLINICAL FOLLOW-UP the hospital, myocardial infarction was excluded, and The findings were compatible with FMD, and he was transferred to the Johns Hopkins Hospital for intervention was postponed due to the large volume of further evaluation. iodinated contrast the patient had received in the preceding On transfer, the patient was taking prednisone days. The initial rise in serum creatinine at the outside 80 mg/day, lisinopril 20 mg/day, amlodipine, and atenolol. hospital was in the setting of renal infarction and adminis- On physical examination, he was afebrile, blood pressure tration of intravenous contrast for CT imaging. He under- 135/77 mm Hg, pulse 64/min, and respirations 20/min. went of the left renal artery 3 months later with Physical findings were significant for normal pulmonary improvement in the mean pressure gradient across the and cardiovascular examinations and the presence stenosis from 12 to 2 mm Hg. Intervention to the right renal of costovertebral angle tenderness bilaterally. artery was deferred, as the upper pole stenosis had Laboratory studies on admission (Table 1) were spontaneously improved. At discharge, the creatinine was notable for mild-to-moderate renal dysfunction with 1.2 mg/dl, and his blood pressure was 122/78 mm Hg off of mild anemia and normal markers of inflammation. antihypertensive therapy.

DISCUSSION Correspondence: C. John Sperati, Division of Nephrology, Department of Here we present a case of bilateral intimal FMD with Medicine, Johns Hopkins University School of Medicine, 1830 E Monument unilateral dissection and infarction in a 46-year-old African- Street, Room 416, Baltimore, MD 21205, USA. E-mail: [email protected] American man initially diagnosed with PAN. Kidney International (2009) 75, 333–336; doi:10.1038/ki.2008.232; published online 4 June 2008 Fibromuscular dysplasia Received 3 December 2007; revised 12 February 2008; accepted 26 Fibromuscular dysplasia is a non-atherosclerotic, non-inflam- February 2008; published online 4 June 2008 matory of largely unknown pathogenesis

Kidney International (2009) 75, 333–336 333 the renal consult CJ Sperati et al.: Intimal fibromuscular dysplasia

Table 1 | Serum, hematological, and urine studies at transfer Sodium 134 mEq/l White blood cell 16,470/mm3 Potassium 4.9 mEq/l Hemoglobin 12.6 g/dl Chloride 96 mEq/l Platelets 200,000/mm3 Total CO2 26 mEq/l ESR 5 mm/h Blood urea 38 mg/dl C-reactive o0.3 mg/dl nitrogen protein TL Creatinine 1.7 mg/dl Urinalysis Negative dipstick Glucose 123 mg/dl Urine microscopic Acellular exam Calcium 9.2 mg/dl Urine protein/ 0.22 gProt/gCr creatinine Albumin 4.0 mg/dl ESR, erythrocyte sedimentation rate.

Figure 3 | Intravascular ultrasound of the left renal artery narrowing demonstrates a focal, thrombosed dissection flap (arrow). TL, true arterial lumen.

and genetic predisposition.2 In one study, 11 of 100 patients had familial renal artery FMD, defined as angiographic evidence of renal artery FMD in at least one sibling.3 These familial cases tended to be bilateral with multifocal lesions. In addition, subclinical arterial disease has been demonstrated in relatives of FMD patients by carotid artery echotracking.4 Although the parents of this patient had hypertension, they did not have a clinical history of underlying FMD. The classification scheme for FMD is based on the arterial Figure 1 | Selective digital subtraction angiography shows 5 focal area of narrowing in the mid left renal artery (arrow). layer involved: intimal, medial, or periadventitial. Medial FMD is further subdivided into medial fibroplasia, perime- dial fibroplasia, and medial hyperplasia. Medial fibroplasia accounts for 70–95% of all cases of FMD and has the classical ‘string of beads’ appearance on angiography due to alternat- ing areas of stenosis and aneurysmal dilatation. Intimal FMD, occurring in only 1–5% of patients, is far less common and has multiple angiographic presentations. Concentric band- like stenoses and smooth tapered lesions similar to those seen in large-vessel have been described.1 Collagen deposition results in a thickened intima, often with fragmentation or duplication of the internal elastic lamina. Duplication appears to be more common in children and adolescents. Concentric stenosis with post-stenotic dilatation is associated with preservation of the elastic lamina on histological examination, whereas irregular, dilated arterial segments are more common with disruption of the elastic lamina.6 Medial hyperplasia also presents with a uniform, Figure 2 | Parenchymal phase of the angiogram reveals area smooth stenosis and can be difficult to differentiate of infarction involving the left upper pole (arrow). angiographically from intimal fibroplasia. The combination of a tapering lesion with a superimposed focal concentric that primarily affects the renal and cerebral arteries, although narrowing, as shown in Figure 1, is most consistent with any arterial bed can be involved.1 Patients with FMD intimal fibroplasia in this patient. Primary intimal fibroplasia can remain asymptomatic or present with hypertension, must be differentiated from secondary causes, such as prior , abdominal angina, , or other signs episodes of malignant hypertension, chronic pyelonephritis, of vascular insufficiency. Proposed etiologic mechanisms or end-stage renal disease. Primary intimal fibroplasia, include hormonal factors, mechanical trauma, metabolic however, involves renal arterial branches larger than an and immunologic factors, intrinsic deficiency of elastic fibers, interlobar artery, as opposed to the involvement of smaller

334 Kidney International (2009) 75, 333–336 CJ Sperati et al.: Intimal fibromuscular dysplasia the renal consult

vasculature seen in secondary processes.7 As such, percuta- (up to 1 cm in size) are considered virtually neous renal biopsy will typically not make a diagnosis of pathognomonic for PAN, with a specificity of 95%.16 FMD, and most cases of FMD do not involve histological Nonetheless, multivessel intimal fibroplasia can have an evaluation of tissue specimens. appearance similar to vasculitis. Moreover, the clinical Renovascular FMD, accounting for 65% of FMD, is features of PAN are due to organ infarction and hemorrhage usually seen in Caucasian women between 15 and 50 years of secondary to necrotizing vasculitis of medium-sized mus- age, although cases have been reported in asymptomatic cular arteries. Common include patients older than 60 years. Renovascular hypertension may constitutional complaints, hypertension, renal impairment, be less common in African-Americans, especially in men.8 peripheral neuropathy, abdominal pain, musculoskeletal Although women comprise 82% of the cases of medial FMD, involvement, skin lesions, and cerebrovascular accidents. only 36% of intimal FMD cases are found in women.9 Intimal PAN is often lethal without prompt treatment, and incorrect FMD is more common in young persons, presenting as diagnosis may lead to improper use of steroids and cytotoxic unifocal or multifocal stenoses that progress to renal artery agents. FMD, however, is a non-inflammatory disease. It is, dissection. When intimal fibroplasia involves multiple therefore, not associated with typical laboratory abnormal- branches of the renal arteries as in this patient, dissection ities of vasculitis, such as anemia, increased erythrocyte and renal ischemia may be more common than with other sedimentation rate, and elevated level of C-reactive protein. subtypes of FMD.3,10,11 Intravascular ultrasound Diagnostic dilemma Given the similarity of FMD and vasculitis by angiography, The differential diagnosis of renovascular FMD includes additional diagnostic modalities may be useful. This patient , vasculitis, and vascular lesions of neuro- underwent renal angiography with IVUS to confirm the fibromatosis (Table 2). There have also been reports of diagnosis of FMD. With IVUS, a dissection flap in the medial fibroplasia associated with disorders of connective left renal artery was diagnosed that was not discerned by tissue, such as Ehlers–Danlos syndrome, Marfan’s syndrome, traditional angiography. Although it is not possible to and Alport’s syndrome.12–14 Atherosclerotic disease typically distinguish a spontaneous dissection due to FMD from one occurs at the ostia or proximal portions of arteries in older caused by the previous catheterization, the presence of an patients who have additional cardiovascular risk factors. arterial dissection would be consistent with the natural Conversely, FMD usually occurs in the distal two-thirds of history of this disease. IVUS has been utilized to gauge the renal arteries. of renal artery and can detect anatomical As in this case, FMD has frequently been misdiagnosed as abnormalities of the arterial wall that are not visualized by vasculitis, and in particular, PAN and giant cell .15,16 traditional angiography.19,20 Classic IVUS findings in FMD Although PAN and FMD have distinct histopathological include a beaded appearance produced by multiple, eccentric, characteristics, both are usually diagnosed angiographically. cleft-like stenoses. In a small study by Sheikh et al.,21 Other techniques to diagnose FMD include duplex ultra- angiography and catheter-based IVUS correlated closely in sonography, CT angiography, and magnetic resonance the determination of arterial lumen diameter (r ¼ 0.81) and angiography. CT angiography has variable efficacy in the cross-sectional area (r ¼ 0.83). Additionally, IVUS provided diagnosis of FMD, with a combination of maximum- structural information not shown by angiography: out of five intensity projection reconstructions and transverse sections stenotic segments, angiography identified atherosclerosis in yielding more definitive diagnosis.17 Contrast-enhanced four and FMD in one, whereas IVUS identified athero- magnetic resonance angiography correlates well with digital sclerosis in three and FMD in two. IVUS also showed three subtraction angiography, with a sensitivity of 97% and arterial dissections, whereas angiography identified only one. specificity of 93%. Magnetic resonance angiography better Gowda et al.20 studied 20 women with drug-resistant detects the ‘string of pearls’ than it does other stenotic hypertension in whom color-flow duplex imaging suggested lesions.18 Renal angiography remains the gold standard for renal artery FMD. Patients underwent renal angiography, the diagnosis of FMD and PAN. Multiple focal visceral/renal revealing classic FMD in only eight, borderline abnormalities in seven, and normal angiograms in five. Conversely, in all patients, IVUS demonstrated endoluminal abnormalities Table 2 | Conditions associated with or mimicking FMD localized to the irregular segments detected by color-flow Atherosclerotic duplex imaging. After balloon angioplasty, IVUS findings Vasculitis Polyarteritis nodosa were completely eliminated in 16 patients and improved in 4. Giant cell arteritis The ability of IVUS to detect vascular abnormalities in Renal artery dissection suspected FMD when angiography is unrevealing supports Vascular lesions of neurofibromatosis the increased use of this modality at centers where it is Ehlers–Danlos syndrome Marfan’s syndrome available. It may prove useful in discriminating indeterminate Alport’s syndrome lesions in patients also at risk for atherosclerotic renal artery a1-Antitrypsin deficiency stenosis. The low-intensity echoes of fibromuscular lesions

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can be readily distinguished from the echogenic appearance routine evaluation of suspected FMD, and the most of calcified plaque.22 A randomized trial, however, will be efficient strategy of monitoring for disease recurrence post- necessary to fully evaluate whether IVUS leads to improved angioplasty, remain to be determined. outcomes over standard imaging approaches. REFERENCES Treatment of FMD 1. Slovut DP, Olin JW. Fibromuscular dysplasia. N Engl J Med 2004; 350: 1862–1871. Currently, the mainstay of intervention is percutaneous 2. Luscher TF, Lie JT, Stanson AW et al. Arterial fibromuscular dysplasia. transluminal balloon angioplasty for patients with difficult- Mayo Clin Proc 1987; 62: 931–952. 3. Pannier-Moreau I, Grimbert P, Fiquet-Kempf B et al. Possible familial to-control hypertension, renal insufficiency, or arterial origin of multifocal renal artery fibromuscular dysplasia. J Hypertens 1997; dissection. 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