Fibromuscular dysplasia in a young female presenting with a ruptured abdominal aortic aneurysm: a rare case report and review of the literature

Abstract

Introduction and importance:

Fibromuscular dysplasia (FMD) is a rare, non-atherosclerotic vascular disease that affects medium-sized arteries such as the renal and carotid arteries. Its involvement in the abdominal aorta, which leads to aneurysm formation, is rare.

Case presentation:

We report the case of a 35-year-old woman who presented with acute abdominal pain, tachycardic but normotensive. Computed tomography angiography (CTA) revealed a ruptured 9-cm fusiform infrarenal abdominal aortic aneurysm (AAA). Emergency open surgical repair with a Dacron graft was performed. Histopathological examination confirmed FMD, showing medial fibroplasia and fragmented elastic fibers. The patient had no risk factors for aneurysm formation, such as hypertension, smoking, or connective tissue disorders. Postoperatively, she recovered uneventfully; mild day-3 hypertension was controlled with amlodipine, and she was discharged on day 7. Follow-up imaging (CTA chest–abdomen and carotid duplex) showed no additional vascular lesions, verifying isolated FMD.

Clinical discussion:

This case highlights the importance of considering FMD in the differential diagnosis of AAAs, particularly in younger patients without conventional risk factors. The pathogenesis of FMD-associated aneurysms remains poorly understood, which complicates early recognition and management. Surgical intervention is the primary treatment for ruptured AAAs, with open repair using synthetic grafts being standard practice. Owing to the rarity of FMD-associated AAAs, data on the efficacy and long-term outcomes of endovascular aneurysm repair in this context are limited. To our knowledge, this is the first documented case of a large, ruptured fusiform infrarenal AAA caused by histologically proven FMD in a young woman.

Conclusion:

FMD should be considered as a potential cause of AAAs in young patients who lack traditional risk factors. Early recognition and appropriate surgical management are crucial to improve patient outcomes. Further research is necessary to better understand the pathophysiology of FMD-associated aneurysms and optimize treatment strategies.

Introduction

Fibromuscular dysplasia (FMD) is a non-atherosclerotic, non-inflammatory vascular disorder that primarily affects medium-sized arteries, most commonly the renal and carotid arteries^[1^]. Involvement of the abdominal aorta is rare, and cases of abdominal aortic aneurysm (AAA) secondary to FMD are exceedingly uncommon^[2^]. Most reported cases of FMD-associated AAA occur in patients without traditional risk factors for aneurysm formation, making early recognition and appropriate management challenging^[3^].

HIGHLIGHTS

• This is the first reported case of a ruptured fusiform abdominal aortic aneurysm (AAA) from isolated aortic fibromuscular dysplasia (FMD).

• Histology confirmed medial fibroplasia with fragmented elastic fibers.

• The patient lacked traditional AAA risk factors like smoking or hypertension.

• FMD should be suspected in young AAA patients with no clear etiology.

AAA is a life-threatening condition that, if ruptured, has a high mortality rate. Although atherosclerosis is the most common etiology, alternative causes such as connective tissue disorders, infections, and vasculopathy must be considered, particularly in younger patients^[4^]. The presence of FMD as a causative factor of AAA has rarely been documented, and its pathophysiology remains unclear^[2^]. Given its rarity, the optimal management approach and long-term outcomes of FMD-related AAA are still under investigation.

Herein, we report the case of a 35-year-old woman who presented with a ruptured infrarenal AAA secondary to isolated aortic FMD. This case underscores the importance of considering non-atherosclerotic causes of AAA in young patients and emphasizes the critical role of histopathological examination in establishing the diagnosis. Additionally, while most reported FMD-related aortic aneurysms have been described as saccular, our case represents a rare occurrence of a ruptured fusiform AAA due to isolated FMD, a presentation that, to our knowledge, has not been documented in the existing literature. This case report has been reported in line with the SCARE checklist^[5^].

Timeline

Time point	Event	Details
Pre-presentation	Sudden onset of symptoms	Severe abdominal pain (exact time not documented)
Day 0 – presentation	Emergency department arrival	35-year-old woman with acute abdominal pain
Day 0 – initial assessment	Clinical examination	Normotensive (110/70 mmHg), tachycardic (108 bpm), diffuse lower abdominal tenderness
Day 0 – laboratory tests	Blood investigations	Hemoglobin: 8.3 g/dL, WBC: 29.44 × 109/L, C-reactive protein: 5.19 mg/L
Day 0 – initial impression	Clinical suspicion	Perforated appendicitis initially suspected
Day 0 – urgent imaging	Computed tomography scan performed	Large, ruptured fusiform AAA (9-cm diameter) identified
Day 0 – emergency surgery	Open surgical repair	18-mm straight Dacron graft placement in the infrarenal position
Day 3	Postoperative complication	Mild hypertension managed with amlodipine
Day 7	Hospital discharge	Stable condition, uneventful recovery

Diagnostic and treatment delays

No significant delays were identified in this case:

• Presentation to imaging: An urgent computed tomography (CT) scan was performed promptly, given the clinical presentation.

• Diagnosis to intervention: Emergency surgical repair was performed immediately after CT confirmation of ruptured AAA.

• Total time from presentation to surgery: Completed within hours of presentation.

  Investigation/follow-up	Timing	Result
  Histopathological examination	Post-surgery	Confirmed fibromuscular dysplasia with medial fibroplasia and fragmented elastic fibers
  Vasculitis panel and serology	During hospitalization	Negative for human immunodeficiency virus, syphilis, and vasculitis
  CT angiogram (chest/abdomen)	During hospitalization	No evidence of vasculitis or FMD in other vessels
  Carotid ultrasound	During hospitalization	No signs of FMD

Case presentation

A 35-year-old Filipino woman, employed as a maid, presented to the emergency department with sudden-onset severe abdominal pain. Her medical history was unremarkable, with no known risk factors for atherosclerosis or AAA. She is a lifelong non-smoker. The patient had no family history of aneurysmal or autoimmune disorders. She had short stature and truncal obesity, features that initially prompted consideration of Turner syndrome and other genetic aortopathies. There were no clinical signs suggestive of connective-tissue disorder.

On initial examination, she was normotensive (110/70 mmHg) but had a resting tachycardia of 108 beats per minute. Abdominal examination revealed diffuse tenderness of the lower abdomen. Laboratory investigations showed a hemoglobin level of 8.3 g/dL, an elevated total white blood cell count of 29.44 × 10⁹/L, and a C-reactive protein level of 5.19 mg/L. Renal function test results were within normal limits, with a urea level of 3.4 mmol/L and a creatinine level of 98 µmol/L. Given her presentation, perforated appendicitis was initially suspected. However, urgent CT revealed a large, ruptured fusiform AAA measuring 9 cm in diameter, with no other abnormalities (Fig. 1).

Figure 1.

Computed tomography (CT) imaging. Computed tomography angiography demonstrating a large fusiform infrarenal abdominal aortic aneurysm with retroperitoneal rupture (A, B). Right (C) and left (D) renal arteries do not show typical features of FMD.

The patient underwent emergency open surgical repair, during which an 18-mm straight Dacron graft was placed in the infrarenal position. The aneurysm sac wall was excised and sent for histopathological analysis. Microscopy confirmed FMD, showing medial fibroplasia and fragmented elastic fibers. Postoperatively, her recovery was uneventful except for mild day-3 hypertension, controlled with amlodipine. Further laboratory tests, including a vasculitis panel and serology for human immunodeficiency virus and syphilis, were negative.

Histopathological examination demonstrated architectural disorganization with extensive intimal proliferation extending into and expanding the tunica media, accompanied by disruption and loss of elastic fibers (Fig. 2). No evidence of atherosclerosis, inflammation, or infection was found. In the absence of other predisposing factors or clinical features of collagen vascular disease, a diagnosis of AAA secondary to isolated aortic FMD was established.

Figure 2.

Photomicrographs show histopathological features observed in the aneurysmal wall tissue. (A) Hematoxylin–Eosin stain, magnification: 20×. There is an irregular thickening of the arterial wall. The intimal layer shows fibrous hyperplasia with proliferation of spindle cells. Medial cystic degeneration is not observed. Adventitia is thinned out. (B) Elastic Van Gieson stain, magnification: 20×. The intima and internal elastic lamina are noted to be indistinct. The elastic fibers (black) are severely lost in the inner parts of the media. They are fragmented and almost replaced by fibrous connective tissue (red) in the outer parts of the media. I: intima; M: media; A: adventitia.

Further imaging, a CT angiogram of the chest and abdomen, performed in accordance with the 2019 International FMD Consensus, showed no vasculitis or additional aneurysms. Both renal and mesenteric arteries were free of FMD-related abnormalities, and carotid duplex ultrasound revealed no signs of FMD. ECG, serial troponins, and transthoracic echocardiography showed no coronary ischemia; coronary tomography angiography (CTA) was therefore not pursued. The patient was discharged in stable condition on postoperative day 7.

Discussion

FMD most commonly involves the renal and carotid arteries; isolated abdominal aortic disease is uncommon, and a large fusiform rupture such as ours is exceptionally rare. This case of a young woman without traditional risk factors therefore widens the clinical spectrum of FMD-associated AAA^[6^].

The pathophysiology of FMD is multifactorial, combining genetic, hormonal, and mechanical factors. Histopathologically, FMD is classified into subtypes based on the predominantly affected arterial layer, with medial fibroplasia being the most common^[1^]. The histological findings in this patient, including intimal proliferation, medial disorganization, and loss of elastic fibers, were consistent with FMD as a causative factor in aneurysm formation. Previous studies have documented only a few cases of FMD leading to AAA^[3,7,8^], making its exact prevalence challenging to ascertain. In contrast to atherosclerotic AAAs, which are strongly linked to traditional cardiovascular risk factors such as smoking, hypertension, and dyslipidemia, aneurysm formation in the context of FMD is exceedingly rare and occurs through a distinct mechanism. In FMD, pathological changes such as medial fibroplasia and fragmentation of elastic fibers result in compromised structural integrity of the arterial wall, which can, in rare instances, predispose to aneurysmal dilatation^[3^]. Such cases are more likely to occur in younger individuals who do not exhibit conventional risk factors for atherosclerotic vascular disease. Recognizing this distinction is crucial, as misdiagnosis or delayed identification of FMD in aneurysm cases can lead to suboptimal management strategies and missed opportunities for appropriate long-term surveillance. Turner syndrome and heritable disorders such as Marfan, Loeys–Dietz, and ACTA2-related disease were excluded by a 46,XX karyotype and absence of syndromic stigmata; a multigene aortopathy panel was discussed but deferred, representing a study limitation.

Although FMD itself is rare, aneurysm or dissection occurs in 20–25% of affected patients, so focused surveillance is warranted. Comprehensive vascular imaging including whole-body CTA and carotid duplex was performed in accordance with the 2019 International FMD Consensus^[9^] and revealed no additional lesions.

Kanamoto et al reported a 69-year-old hypertensive woman with a 3.6-cm saccular aneurysm at the terminal abdominal aorta, in which histopathology confirmed FMD with fragmented elastic fibers in the inner media^[7^]. Similarly, Odero et al described a 77-year-old man with claudication and severe infrarenal aortic hypoplasia, which led to the formation of a 5-cm fusiform distal aortic aneurysm, likely as a result of post-stenotic dilatation. This was successfully managed with a bifurcated Dacron graft^[8^]. Together with Kanamoto’s report, these cases highlight the diverse manifestations of aortic involvement in FMD and underscore the importance of considering FMD in the differential diagnosis of aneurysmal disease, particularly in patients without traditional risk factors. However, unlike these previously reported cases, which either involved post-stenotic fusiform or saccular aneurysms in association with anatomical abnormalities, our patient demonstrated a ruptured fusiform AAA in the setting of isolated aortic FMD without adjacent hypoplasia. This presentation is extremely rare and expands the spectrum of FMD-associated aneurysms, suggesting that diffuse circumferential dilatation may also occur as a primary manifestation of isolated FMD, even in the absence of classic predisposing factors.

Diagnosis of FMD-associated AAA requires a high index of suspicion, especially in young patients without classical atherosclerotic risk factors. CTA remains the imaging modality of choice, providing detailed visualization of arterial wall abnormalities, aneurysmal changes, and potential involvement of other vascular territories^[8,10^]. In this case, CTA identified a large fusiform AAA with no evidence of FMD in the renal, mesenteric, or carotid arteries, reinforcing the localized nature of the disease process.

Surgical repair is the standard treatment for ruptured AAA, regardless of etiology. Given the aneurysm’s size and rupture, open repair with a Dacron graft was performed. While endovascular aneurysm repair is increasingly used for AAA^[11^], its role in FMD-related cases remains uncertain due to limited data and concerns about durability in non-atherosclerotic vessels. In our case, postoperative hypertension required antihypertensive therapy, a common FMD complication often linked to renal artery involvement^[1^], though imaging was normal. Persistent hypertension underscores the need for continued cardiovascular monitoring and blood pressure management to prevent further complications.

While long-term follow-up is essential in patients with FMD, the intensity and modality of surveillance should be individualized based on disease severity, vascular bed involvement, and clinical presentation. According to current international guidelines, all patients should undergo periodic clinical evaluation, including assessment of blood pressure, vascular symptoms, and medication adherence, with follow-up at least annually by a healthcare provider experienced in FMD management. Imaging surveillance should be tailored to each patient’s risk profile and vascular findings, including the presence and size of aneurysms, extent of arterial lesions, and history of revascularization procedures^[9^]. In our patient, given the occurrence of a ruptured aneurysm, more intensive imaging follow-up and strict blood pressure control are warranted to monitor for potential disease progression and to prevent future vascular events.

This case uniquely reports a ruptured fusiform AAA caused by isolated aortic FMD in a young female without traditional risk factors, confirmed through detailed histopathology. The comprehensive diagnostic workup and successful multidisciplinary surgical management highlight its relevance across vascular surgery, pathology, radiology, and internal medicine. It emphasizes the need to consider rare non-atherosclerotic causes in atypical aneurysm presentations.

Being a single case, the findings lack generalizability and long-term follow-up data. Systemic vascular mapping and comprehensive genetic panel testing were not performed, limiting the full assessment of disease extent and etiology. Future cases should incorporate molecular testing to strengthen phenotype–genotype correlations, particularly given recent advances in FMD genetics, including identification of multiple risk loci and rare variants in genes such as PHACTR1, COL5A1, and PTGIR. Additionally, the suitability of endovascular repair in FMD-related aneurysms remains uncertain due to limited evidence.

Conclusion

In conclusion, this case illustrates a rare and atypical presentation of FMD-associated AAA in a young female without traditional risk factors. Notably, the aneurysm was fusiform in morphology, which is exceedingly uncommon in non-atherosclerotic aneurysmal disease and has been rarely documented in the literature. This expands the recognized clinical spectrum of FMD-related vascular complications. Our case highlights the importance of thorough diagnostic evaluation, including histopathological confirmation, and emphasizes the role of tailored surgical management in achieving favorable outcomes. Further research is warranted to better understand the natural history, optimal management, and long-term prognosis of FMD-associated aneurysms.

Ethical approval

This case report was conducted in accordance with ethical guidelines and institutional policies. Formal IRB approval was not required as per institutional regulations.

Consent

Written informed consent was obtained from the patient for publication of this case report and accompanying images.

Sources of funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Author contributions

M.F. contributed to drafting the manuscript, conducting the literature review, data collection, and critically revising the manuscript. S.A. performed the literature review, data collection, and drafted the initial manuscript. H.M. was involved in the clinical management of the patient, literature review, and critical revision of the manuscript. N.S.B.G. carried out the histopathological analysis and interpretation of findings. M.B. oversaw the clinical management, provided supervision, conceptualized and designed the study, critically revised the manuscript, and contributed to the manuscript writing.

Conflicts of interest disclosure

The authors have no conflicts of interest to declare.

Research registration unique identifying number (UIN)

Not applicable.

Guarantor

Mohamed Baguneid.

Provenance and peer review

Not commissioned; externally peer reviewed.