Segmental Arterial Mediolysis: CTA Findings at Presentation and Follow-Up

A case of rectal cancer complicated with segmental arterial mediolysis (SAM) safely treated with curative resection - A case report

INTRODUCTION

Recent advances in diagnostic imaging techniques have led to an increasing number of case reports of segmental arterial mediolysis (SAM). However, reports of abnormalities associated with SAM of abdominal organs, including the bowel, are limited. SAM, a rare vascular disease that causes spontaneous intra-abdominal bleeding, including shock and intestinal ischemia, has been reported to be associated with high mortality, but it has not been reported to coexist with rectal cancer.

CASE PRESENTATION

A 74 year-old male was referred to our hospital with a rectal cancer and he was admitted for further examination. Computed tomography angiography (CTA) revealed dissection and aneurysm in the celiac artery, superior mesenteric artery (SMA), and the inferior mesenteric artery were dilated, leading to a diagnosis of SAM.

CLINICAL DISCUSSION

Surgery for rectal cancer requires cutting the inferior mesenteric artery. The risk of bleeding during surgery increases when SAM is associated with the inferior mesenteric artery. The radical surgery for rectal cancer was executed without complications, including significant bleeding. This was achieved through careful management of SAM, meticulous control of blood pressure throughout the surgical procedure, and the delicate treatment of the SMA. A pathological diagnosis of the resected inferior mesenteric artery at the time of radical surgery was performed, and a definitive diagnosis of SAM was made.

CONCLUSION

We present a first known case in which high anterior resection was successfully performed for rectal cancer complicated by SAM. The relationship between cancer and SAM is unclear and further case accumulation is needed.

Gallbladder hemorrhage associated with segmental arterial mediolysis: a case report

BACKGROUND

Gallbladder hemorrhage is a rare but fatal condition. The reported causes of gallbladder hemorrhage include iatrogenesis, atherosclerotic changes in the cystic arteries, acute cholecystitis or cholelithiasis, malignancy, trauma, hemophilia, pseudoaneurysm, and the use of oral anticoagulant medications. Recently, segmental arterial mediolysis (SAM) has been reported as a possible etiology of life-threatening abdominal, retroperitoneal, and intracranial hemorrhages. However, no previous reports have described the association between gallbladder hemorrhage and SAM.

CASE PRESENTATION

A 59-year-old man was transferred to our hospital complaining of upper abdominal pain and vomiting. Contrast-enhanced computed tomography revealed high-density images of the gallbladder and common bile duct. However, there were no obvious findings of gallstones, cholecystitis, tumors, or aneurysms. He was diagnosed with gallbladder hemorrhage and bile duct obstruction. We performed a laparoscopic cholecystectomy after endoscopic biliary drainage. The gross appearance of the surgically resected specimen showed 12 small (3-12 mm), slightly elevated lesions on the gallbladder mucosa. Histologically, these slightly elevated lesions consisted of dilated muscular arteries of the gallbladder wall with fibrinoid degeneration of the media and focal loss of the internal and external elastic laminae. The histopathological diagnosis was confirmed as SAM.

CONCLUSIONS

To the best of our knowledge, this is the first reported case of a gallbladder hemorrhage associated with SAM. Our case report shows that SAM can cause gallbladder hemorrhage, suggesting that SAM should be considered in the differential diagnosis of gallbladder hemorrhage.

Differentiating between segmental arterial mediolysis and other arterial vasculopathies to establish an early diagnosis - a systematic literature review and proposal of new diagnostic criteria

Segmental arterial mediolysis (SAM) is a rare vascular disease, characterized by acute but transient vulnerability of the wall of medium-sized arteries. The most characteristic feature of SAM is its biphasic course: an injurious phase marked by acute weakness of the arterial wall leading to acute dissection and/or hemorrhage, followed by a reparative phase in which granulation tissue and fibrosis restore the injured arterial wall. Residual stenosis, aneurysms, and/or arterial wall irregularities may remain visible on future imaging studies. Differentiating between SAM and other arterial vasculopathies is difficult due to its similarities with many other vascular diseases, such as vasculitis, fibromuscular dysplasia, inherited connective tissue disorders, and isolated visceral artery dissection. In this systematic review, we provide an overview on SAM, with an emphasis on the differential diagnosis and diagnostic work-up. We propose new diagnostic criteria to help establish a prompt diagnosis of SAM, illustrated by case examples from our multidisciplinary vascular clinic.

Rheumatic masqueraders: mimics of primary vasculitis - a case-based review

INTRODUCTION

Vasculitis conditions are often serious and sometimes fatal diseases, therefore it is paramount to diagnose correctly and treat appropriately. Mimics of primary vasculitis can include either non-inflammatory syndromes or secondary vasculitis where the underlying etiology of the vasculitis is being driven by infection, malignancy, drug-effect or other.

AREAS COVERED

This review comprises six individual cases of vasculitis mimics. Each case is presented and the clinical, radiographic, and histological features that distinguish the case from primary vasculitis are highlighted. Key mimics in large, medium and small vessel vasculitis are outlined.

EXPERT OPINION

The diagnosis of vasculitis requires a comprehensive assessment of clinical, radiographic, and histologic features. Clinicians should be familiar with mimics of primary vasculitis conditions. In the case of non-inflammatory mimics, it is important to differentiate from primary vasculitides in order to avoid unnecessary and potentially harmful immunosuppression. For cases of secondary vasculitis, identification of the correct etiologic cause is critical because treatment of the underlying stimulus is necessary for successful management and outcomes.

Pancreaticoduodenal Artery Aneurysm Rupture Presenting as Duodenal Obstruction Successfully Treated with Early Transcatheter Arterial Embolization: A Case Report of Suspected Segmental Arterial Mediolysis

Visceral aneurysms are a rare but important form of abdominal vascular disease. Rupture of the aneurysms leads to serious symptoms, such as acute abdomen or abdominal bleeding. However, duodenal obstruction due to arterial rupture of an aneurysm is very rare. We herein report a 50-year-old woman with suspected segmental arterial mediolysis (SAM) who was first diagnosed with acute abdomen and duodenal obstruction. Rupture of a pancreaticoduodenal artery aneurysm was confirmed, and she was treated with transcatheter arterial embolization. In cases of acute abdomen, SAM is a rare but important possibility to consider as a differential diagnosis.

Transarterial embolization for ruptured pancreaticoduodenal artery aneurysm due to segmental arterial mediolysis combined with median arcuate ligament syndrome: a case report

A 75-year-old female with a history of Parkinson's disease treatment and hypertension presented at the emergency section with sudden onset of right abdominal pain. Contrast-enhanced computed tomography revealed beaded irregular stenosis and dilation of the superior mesenteric artery (SMA) and an aneurysm in the branch of the pancreaticoduodenal artery (PDA) that communicates with the common hepatic artery and SMA. Additionally, a hematoma had formed in the retroperitoneal space, and extravasation of contrast medium from the pancreaticoduodenal artery aneurysm (PDAA) into the hematoma was observed. The celiac artery (CA) was compressed by the median arcuate ligament; stenosis of the CA at its origin and dilation on the distal side were observed. Based on the imaging findings, it was diagnosed that PDAA was ruptured, SMA developed segmental arterial mediolysis (SAM), and CA developed median arcuate ligament syndrome (MALS). The ruptured PDAA was thought to be caused by SAM combined with MALS. Transcatheter arterial embolization (TAE) was performed for the ruptured PDAA. To the best of our knowledge, there have been no reports of TAE for a ruptured PDAA caused by SAM and MALS. After TAE, the PDAA did not re-rupture.

Superficial temporal artery aneurysm with segmental arterial mediolysis: a case report

Segmental arterial mediolysis (SAM) is a rare non-arteriosclerotic and non-inflammatory vascular disease. Superficial temporal artery (STA) aneurysms are usually associated with trauma, surgery, and hair transplantation. Spontaneous aneurysms of the STA are uncommon, but an STA aneurysm caused by SAM is rare. We report a 70-year-old woman with a spontaneous aneurysm of the STA. The mass in the left parietal region was pulsatile and gradually enlarged in size without any history of head trauma. The mass was successfully removed by surgery and was proved histopathologically to be a true aneurysm with SAM.

Endovascular treatment of an isolated iliac artery aneurysm associated with segmental arterial mediolysis

Segmental arterial mediolysis is a noninflammatory nonatherosclerotic vasculopathy of uncertain etiology characterized by dissection and/or aneurysm formation. It affects medium-to-large arteries, primarily the celiac, superior mesenteric, and renal arteries. Iliac involvement is rare, and its specific treatment has not been described. We detail a patient who presented with intrabdominal hemorrhage from a ruptured right colic artery aneurysm. He underwent transcatheter arterial embolization followed by right hemicolectomy. Histopathology confirmed the diagnosis of segmental arterial mediolysis. Endovascular treatment of a 3-cm iliac artery aneurysm was performed 18 months later. There was successful exclusion of the aneurysm demonstrated on computed tomography angiography at 10 years.

A case of transcatheter arterial embolization for intraperitoneal hemorrhage due to giant hepatic segmental arterial mediolysis

This study aimed to demonstrate the effect of transcatheter arterial embolization (TAE) on hepatic segmental arterial mediolysis (SAM). The patient, a 68-year-old female, suddenly developed right upper abdominal pain in October 2021, which was initially relieved. However, she was rushed to a local hospital the next day when her abdominal pain recurred. An abdominal computed tomography scan suggested a ruptured hepatic aneurysm; therefore, she was transferred to our hospital and admitted on the same day. On the first day after admission, she underwent emergency catheterization and N-butyl-2-cyanoacrylate (NBCA)/lipiodol embolization for an aneurysm in the hepatic S6. A multi-detector computed tomography on hospital day 8 to probe for extrahepatic lesions revealed multiple beaded irregularities in the superior mesenteric and bilateral renal arteries. A head magnetic resonance angiography performed on the ninth day showed no aneurysms or irregularities. She did well after TAE, did not have rebleeding, and was discharged on hospital day 16. Rupture of an aneurysm associated with SAM occurs frequently in the colonic and gastroepiploic arteries, and rupture of a hepatic aneurysm is relatively rare. TAE hemostasis was able to save the patient by preventing intraperitoneal bleeding caused by hepatic segmental arterial mediolysis.

Acute abdominal pain: a challenging diagnosis

We hereby describe a case of an acutely ill 41-year-old male without any medical history who presented with an acute abdomen in the emergency department. An abdominal CT showed a dissection of the coeliac trunk and infarction of the spleen. Because of a presumed diagnosis of vasculitis he was started on high dose IV steroids. However, after additional testing the diagnosis of segmental arteriolar Mediolysis (SAM) was made. In this case report we describe the presentation, diagnosis, treatment and follow-up of this patient and provide the readers with background about common differential diagnosis and criteria for diagnosing SAM.

Imaging of intestinal vasculitis focusing on MR and CT enterography: a two-way street between radiologic findings and clinical data

Diagnosis of intestinal vasculitis is often challenging due to the non-specific clinical and imaging findings. Vasculitides with gastrointestinal (GI) manifestations are rare, but their diagnosis holds immense significance as late or missed recognition can result in high mortality rates. Given the resemblance of radiologic findings with some other entities, GI vasculitis is often overlooked on small bowel studies done using computed tomography/magnetic resonance enterography (CTE/MRE). Hereon, we reviewed radiologic findings of vasculitis with gastrointestinal involvement on CTE and MRE. The variety of findings on MRE/CTE depend upon the size of the involved vessels. Signs of intestinal ischemia, e.g., mural thickening, submucosal edema, mural hyperenhancement, and restricted diffusion on diffusion-weighted imaging, are common in intestinal vasculitis. Involvement of the abdominal aorta and the major visceral arteries is presented as concentric mural thickening, transmural calcification, luminal stenosis, occlusion, aneurysmal changes, and collateral vessels. Such findings can be observed particularly in large- and medium-vessel vasculitis. The presence of extra-intestinal findings, including within the liver, kidneys, or spleen in the form of focal areas of infarction or heterogeneous enhancement due to microvascular involvement, can be another radiologic clue in diagnosis of vasculitis. The link between the clinical/laboratory findings and MRE/CTE abnormalities needs to be corresponded when it comes to the diagnosis of intestinal vasculitis.

Splenic Artery Pseudoaneurysms: The Role of ce-CT for Diagnosis and Treatment Planning

Splenic artery pseudoaneurysm (PSA) is a contained vascular wall lesion associated with a high mortality rate, generally related to pancreatitis, trauma, malignancy, iatrogenic injury, and segmental arterial mediolysis. Computed tomography angiography allows us to visualize the vascular anatomy, differentiate a PSA from an aneurysm, and provide adequate information for endovascular/surgical treatment. The present review reports on the main state-of-the-art splenic artery PSA diagnosis, differentiating between the pros and cons of the imaging methods and about the endovascular treatment.

Clinical Presentation, Imaging, and Management of Segmental Arterial Mediolysis: A Rare Vascular Disorder

Objectives  Our objective was to analyze the clinical presentation, imaging findings, and the management of segmental arterial mediolysis (SAM) in different case scenarios within our medical institution.

Materials and Methods  We retrospectively analyzed 13 cases of SAM in our institution from July 2017 to March 2020. The images from the cases were collected from picture archiving and communication system (PACS) along with other pertinent clinical information from the hospital's information system. All the patients we studied underwent contrast-enhanced computed tomography (CT) using a third-generation Siemens SOMATOM Force dual-source CT scanner. Once the dual-phase scanning was completed, the images were analyzed using the workstation's syngo.via software.

Results  Three out of the 13 cases required stent-grafting of the renal/celiac artery, and the involved branch of the superior mesenteric artery was embolized in one case. The rest of the cases were managed conservatively with antiplatelets/anticoagulants. Subsequent follow-ups of the patients were conducted and showed stabilization/regression of the initial findings without finding any evidence of worsening.

Conclusion  SAM should be considered when making a differential diagnosis of acute abdominal pain when associated with dissection or aneurysms in splanchnic arteries, and in cases of unexplained intra-abdominal hemorrhaging. The radiologist needs to be aware of this possibility to raise suspicion, alert the clinician, and guide appropriate management.

Segmental arterial mediolysis: a rare cause of an acute abdomen

Segmental arterial mediolysis (SAM) is a nonatherosclerotic, noninflammatory and nonimmune arteriopathy of unknown aetiology. We present the case of a 43-year-old male who presented to the emergency department with abdominal pain. A computed tomography of abdomen and pelvis showed a narrow, hypodense superior mesenteric artery after the origin, raising the possibility of thrombus or vasculitis. He was commenced on rivaroxaban and steroids. He subsequently presented with an acute abdomen in a collapsed state. Repeat imaging of his abdomen and pelvis revealed an ischaemic ileal segment and caecum. He required an emergency laparotomy with resection of the ischaemic segment and formation of a double-barrelled stoma. SAM is an important diagnosis for clinicians and radiologists to be aware of, given the risks of life-threatening haemorrhage and acute organ ischaemia. This is a commonly overlooked cause of abdominal pain, where an early diagnosis with lifestyle modifications may prevent disease progression and subsequent development of life-threatening complications.

Rapid Formation and Rupture of Multiple Abdominal Pseudoaneurysms: A Life Threatening Case of Segmental Arterial Mediolysis

We present a 62-year-old gentleman with rapidly forming abdominal pseudoaneurysms due to segmental arterial mediolysis (SAM). With rupture of his pseudoaneurysms, he underwent angiography and successful coil embolisation. In this case, we demonstrate the potential for rapid progression of pseudoaneurysms in SAM, with the need for prompt diagnosis and urgent endovascular intervention.

Multiple abdominal artery dissections: how to distinguish two rare diseases

A 59-year-old woman was referred to the emergency room with acute abdominal pain. A CT scan revealed multiple dissections and microaneurysms of the superior mesenteric, the hepatic and the renal arteries. Stenting of the superior mesenteric artery was required. A non-invasive diagnostic procedure was instrumental to establish the diagnosis and guide appropriate treatment, which resulted in a rapid and sustained recovery.

A case presenting as fatal subarachnoid hemorrhage due to segmental arterial mediolysis associated with Crohn's disease

BACKGROUND

Segmental arterial mediolysis (SAM) is a rare arterial pathology and can cause rupture or dissection of the intracranial arterial wall. The etiology is unveiled, but vasospastic stimuli such as migraine are considered as a possible cause of SAM. We present the first case of subarachnoid hemorrhage (SAH) due to SAM associated with Crohn's disease and migraine, and discuss the possible contribution of Crohn's disease to the development of SAM besides migraine.

CASE DESCRIPTION

A 33-year-old man with Crohn's disease, which had been treated with adalimumab, repeatedly underwent 3-tesla magnetic resonance (MR) imaging and angiography for severe headache due to migraine and the subsequent development of fatigue in the left arm and both legs. At 7 months after the last MR imaging studies showing no abnormalities, he had a sudden onset of severe SAH, which was caused by rupture or dissection of the terminal portion in the right internal carotid artery. As his brain-stem reflexes were absent, the patient was conservatively treated and died 6 days after the ictus. By postmortem histopathological examination, SAM was diagnosed as the cause of SAH. Vasa vasorum was also observed around the rupture point.

CONCLUSIONS

Our case suggests that: 1) the formation of vasa vasorum may be an antecedent pathology for vessel rupture of the fragile arterial wall affected by SAM, and 2) vasospastic nature of both Crohn's disease and migraine may contribute to the development of intracranial SAM.

Fatal hemorrhage after tonsillectomy

This is the first report of a segmental mediolysis occurring in arterioles, affecting the neck/tonsillar region and leading to a fatal hemorrhage after a tonsillectomy in a 20-year-old woman. Arteriolar mediolysis could be observed in tissue layers about 2 cm distant from the tonsillectomy region. Reparative changes were observed in the carotid and small neck arteries as well as in only one intramyocardial arteriole; however, no other vascular regions typically reported in segmental mediolysis arteriopathy were affected and aneurysm formation was not observed. No family history of vascular disease or hypertension was known. Pathophysiologically, previously reported reasons for post-tonsillectomy bleeding could be excluded. Segmental mediolysis may represent a wider spectrum of affected arteriolar vessels besides the reported small and medium sized arteries leading to aneurysms, which impedes radiographic diagnosis.

Segmental Arterial Mediolysis (SAM) Leading to Chronic Renal Insufficiency

Background

Segmental arterial mediolysis (SAM) is a rare self-limiting non-atherosclerotic, non-inflammatory vasculopathy. SAM typically affects the visceral arteries of the abdomen to include the celiac, mesenteric, and renal arteries. SAM has a favorable prognosis in most cases with an asymptomatic course but can have mortality rates as high as 50% due to acute aneurysmal rupture. Very few cases of adverse long-term sequelae involving SAM have been described, and this report of chronic kidney disease represents a sentinel case illustrating that chronic disease can and does occur as a result of SAM and should be investigated for at follow-up.

Case Presentation

In this case report, we describe a case of a 45-year-old male with erectile dysfunction but without any readily identifiable risk factors for chronic kidney disease (CKD) or vasculopathy, who presented with bilateral renal infarction and parenchymal infarcts due to SAM and who subsequently developed CKD at follow-up. We conduct a mini-literature review that discusses the pathogenesis of SAM in the context of vasospastic diseases, as well as compares the outcomes of observation-only, versus medical-management, versus endovascular-interventions in patients with SAM.

Conclusion

This is the first case to our knowledge of CKD occurring as an outcome of SAM without any preceding significant comorbidity, highlighting that whereas SAM is of itself rare and typically resolves, chronic disease can linger and should be evaluated for on follow-up. Further, we argue that radiological evidence of precursor vasospastic disease may exist in several locations apart from the index lesion and thus warrants wider whole-body radiographic exploration for lesions as an opportunity to prevent chronic sequelae as illustrated in this case report from occurring. Finally, a review of published case-series suggests that disease progression is less likely to occur after endovascular-intervention compared to observation-only or medical management and the risk of intervention vs conservative management should therefore be discussed with the patient.

Clinically Suspected Segmental Arterial Mediolysis of the Splanchnic Arteries: A Report of 2 Rare Cases

Case series

Patients: Female, 89-year-old • Male, 52-year-old

Final Diagnosis: Segmental arterial mediolysis

Symptoms: Abdominal pain • bleeding

Medication: —

Clinical Procedure: —

Specialty: Radiology

Natural History of Unruptured Visceral Artery Aneurysms Due to Segmental Arterial Mediolysis and Efficacy of Transcatheter Arterial Embolization: A Retrospective Multiinstitutional Study in Japan

OBJECTIVE. The purpose of this study was to clarify the natural history of unruptured visceral artery aneurysms due to segmental arterial mediolysis and the efficacy of transcatheter arterial embolization. MATERIALS AND METHODS. Patients with a pathologic or clinical diagnosis of visceral artery aneurysms due to segmental arterial mediolysis between 2005 and 2015 were enrolled. For patients with clinical diagnoses, images were collected and assessed by central radiologic review. To clarify the natural history of unruptured aneurysms, the morphologic changes were assessed. The efficacy and safety of transcatheter arterial embolization for aneurysms due to segmental arterial mediolysis were evaluated. RESULTS. Forty-five patients with 123 aneurysms due to segmental arterial mediolysis were enrolled. Among the 123 aneurysms, 70 unruptured aneurysms were evaluated for natural history. Forty-five of the 70 (64%) aneurysms had no change in morphology. Among the other 25 aneurysms, nine (13% of the 70) were reduced in size, 13 (19%) disappeared, and three (4%) were newly found at follow-up. Aneurysms of the middle colic artery were ruptured in 10 of 11 (91%) cases. Transcatheter arterial embolization was performed on 45 aneurysms and was successful in all cases but caused slight arterial injury in three cases (6.7%). CONCLUSION. At initial diagnosis, unruptured aneurysms due to segmental arterial mediolysis are likely to be stable or to resolve, but the risk of rupture of aneurysms of the middle colic artery appears high. Transcatheter arterial embolization is a useful treatment, but careful manipulation is necessary.

Ileocolic arterial aneurysm associated with segmental arterial mediolysis: A case report

OBJECTIVES

Segmental arterial mediolysis is a rare disease that most commonly affects the superior mesenteric artery among abdominal arteries. However, aneurysms involving the ileocolic arterial branch of the superior mesenteric artery are extremely rare. Here, we describe the treatment of a patient with an ileocolic arterial aneurysm suspected to have occurred secondary to segmental arterial mediolysis.

METHODS

We confirmed the diagnosis of ileocolic arterial aneurysm, which showed the characteristic "string-of-beads" appearance of the distal main trunk of the superior mesenteric artery on angiography. We performed endovascular coil embolization for the aneurysm, and for both the inflow and outflow vessels. After confirming that the aneurysm was no longer visible, the treatment was completed.

RESULTS

There were no clinical findings suspicious of ischemic enteritis or intestinal necrosis after embolization. We confirmed that the ileocolic arterial aneurysm was not observed on computed tomography angiography one month after treatment.

CONCLUSIONS

While development of an ileocolic arterial aneurysm associated with segmental arterial mediolysis is very rare, it is at a high risk of sudden rupture. Therefore, coil embolization is a useful intervention in such patients and can be implemented based on the size and morphology of the aneurysm.

Cross-Sectional Imaging Evaluation of Vascular Lesions in the Gastrointestinal Tract and Mesentery

Gastrointestinal (GI) tract and mesenteric vascular lesions can have various clinical presentations, of which GI bleeding is the most common. This collection of pathology is highly variable in etiology ranging from occlusive disease to vascular malformations to trauma to neoplasms which makes for a challenging workup and diagnosis. The advent of multiple imaging modalities and endoscopic techniques makes the diagnosis of these lesions more achievable, and familiarity with their various imaging findings can have a significant impact on patient management. In this article, we review the gamut of GI tract and mesenteric vascular lesions and their associated imaging findings.

Segmental Arterial Mediolysis: An Under-Recognized Cause of Chronic Abdominal Pain

Segmental arterial mediolysis (SAM) is a non-inflammatory, non-atherosclerotic vasculopathy mostly involving the abdominal arteries. SAM was recently recognized as a more prevalent aetiology of abdominal pain than initially thought by healthcare providers. It is still a commonly missed diagnosis in patients with recurrent emergency room (ER) visits for abdominal pain. Most published case reports in the past have highlighted catastrophic sequelae such as intra-abdominal haemorrhage requiring surgical intervention. We report a case of SAM where the diagnosis was initially missed. After diagnosis, conservative medical management was offered which led to clinical improvement.

LEARNING POINTS

To recognize segmental arterial mediolysis (SAM) as a cause of chronic abdominal pain in the middle-aged and elderly population.To differentiate SAM from inflammatory vasculitis and atherosclerotic conditions.For cases with mild symptoms and haemodynamic stability, conservative management such as early lifestyle modifications, hypertension and hyperlipidaemia control and regular imaging follow-up should be offered.

ACR Appropriateness Criteria® Nonatherosclerotic Peripheral Arterial Disease

A broad range of nonatherosclerotic diseases affect the peripheral arteries. The appropriate initial diagnostic imaging studies vary, depending upon the clinical presentation and suspicion of disease. Accurate vascular imaging relies upon visualization of the vessel lumen, vessel wall, and surrounding soft-tissue structures, with some modalities also offering the ability to characterize blood flow direction and velocity. Furthermore, nonvascular findings are often paramount in supporting a suspected clinical syndrome or guiding surgical management. The scenarios discussed in this document include the initial evaluation of suspected popliteal entrapment syndrome, external iliac artery endofibrosis, lower-extremity inflammatory vasculitides, dissection or connective tissue disease, noninflammatory vascular disease, and vascular trauma. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Segmental arterial mediolysis: a commonly overlooked aetiology of acute abdominal pain

Segmental arterial mediolysis (SAM) is an uncommon condition and commonly missed diagnostic aetiology of acute abdominal pain, initially described in 1976. SAM is a non-inflammatory, non-atherosclerotic vasculopathy mostly involving the abdominal arteries with notable asymmetric involvement of the walls of the mesenteric arteries and their branches. Clinical presentation ranges from postprandial abdominal discomfort suggestive of mesenteric ischaemia to intra-abdominal bleeding. Pathophysiological explanation and prognosis of these cases are not well understood and therefore no clear guidelines for management exist. In this case report, we emphasise the imaging modalities used to reach the diagnosis and the management options available.

Natural history and management outcomes of segmental arterial mediolysis

BACKGROUND

Segmental arterial mediolysis (SAM) is a poorly understood, nonatherosclerotic, noninflammatory disease resulting from arterial medial degeneration. Patients may present with aneurysm, dissection, stenosis, or bleeding from visceral or renal arteries. Treatment algorithms are poorly characterized.

METHODS

A retrospective review of all patients diagnosed with SAM was performed at our institution. Patients were identified by established criteria that include clinical presentation in combination with radiographic and serologic findings. Demographics, presenting symptoms, diagnostic evaluation, management, and outcomes were reviewed.

RESULTS

There were 117 patients diagnosed with SAM between 2000 and 2016; 67.5% (n = 79) were male. Mean age was 52.7 years (range, 23.4-90 years); 69.2% (n = 81) presented with acute abdominal pain, 22.2% (n = 26) with flank pain, and 19.7% (n = 23) with back pain; 15.4% (n = 18) had abdominal pain longer than 30 days; 13.7% (n = 16) had acute hypertension, and 5.1% (n = 6) were hypotensive; 10.3% (n = 12) were asymptomatic. There were 93 (79.5%) dissections and 61 (52.1%) aneurysms. Hemorrhage was seen in 10 (8.5%). The celiac axis was affected in 54.7% (n = 64), renal arteries in 49.6% (n = 5 8), superior mesenteric artery in 43.6% (n = 51), and inferior mesenteric artery in 2.6% (n = 3). After diagnosis of SAM, aspirin was prescribed in 60.7% (n = 71). Statins were prescribed in 29.9% (n = 35). Antihypertensive medications were prescribed in 65% (n = 76), including beta blockers in 42.7% (n = 50); 40.2% (n = 47) of patients were prescribed anticoagulation. Interventions were performed in 26 (22%) patients; 13 had endovascular intervention only, 9 open surgery only, and 4 open and endovascular interventions. Of the 17 patients undergoing endovascular intervention, 19 procedures were performed, most commonly embolization (78.9% [n = 15]), followed by stenting (10.5% [n = 2]). Of the 13 patients undergoing open surgery, 14 procedures were performed, including arterial bypass (50% [n = 7]) and splenectomy with aneurysm ligation (15.4% [n = 2]). Other surgery involved thrombectomy (21.4% [n = 3]) and angioplasty (14.3% [n = 2]). Only 11.5% (n = 3) experienced a perioperative complication, including one hematoma, one abscess, and one death secondary to ongoing hemorrhage. Follow-up imaging was performed in 96.6% (n = 112). Mean follow-up was 1258 days (range, 2-5017 days). Of these, 27.7% (n = 31) had regression, 43.8% (n = 49) stability, and 28.6% (n = 32) progression. Average time between initial diagnosis and progression was 666 days.

CONCLUSIONS

SAM is an uncommon disease that may require intervention; it is therefore important that the vascular surgery community be aware of this disease. Follow-up imaging is required to monitor for disease progression.

Peripheral Vascular Imaging Focusing on Nonatherosclerotic Disease

A variety of nonatherosclerotic diseases affect the arteries of the pelvis and lower extremities. Chronic repetitive traumatic conditions, such as popliteal entrapment and external iliac artery fibroelastosis, vasculitis and connective tissue diseases, and noninflammatory vascular diseases, are a few of the more commonly encountered nonatherosclerotic peripheral vascular diseases. Ultrasound, computed tomography angiography, and magnetic resonance angiography are essential in the initial assessment and management of patients with peripheral vascular disease.

Practical approach to vasculitides in adults: an overview of clinical conditions that can mimic vasculitides closely

Primary systemic vasculitides are rare diseases affecting blood vessel walls. The type and patterns of distribution of the organs affected usually reflect the size of the vessels predominantly involved, and the patterns of clinical manifestations are generally useful to reach a specific diagnosis. However, presenting symptoms may lack adequate specificity for a prompt diagnosis, leading to a diagnostic (and therapeutic) delay, often causing irreversible damage to the affected organs. Due to their rarity and variable clinical presentation, the diagnosis of primary vasculitides could be challenging for physicians. Vasculitis mimickers, i.e. the clinical conditions that could be likely mistaken for vasculitides, need to be carefully ruled out, especially before starting the immunosuppressive therapy. We present here a practical approach to the diagnosis of primary systemic vasculitides involving large, medium and small size vessels, and reviewed most of the conditions that could mimic primary systemic vasculitides.

Fibromuscular dysplasia presenting with a deep vein thrombosis

A 41-year-old male patient presented with isolated right lower limb swelling. An ultrasound scan showed right external iliac and femoral vein deep vein thrombosis due to extrinsic compression by an aneurysm of the right common iliac artery. Investigations including imaging and a tissue biopsy of right and left femoral arteries confirmed a rare clinical presentation of fibromuscular dysplasia involving iliac, coeliac, renal and pulmonary vessels. The common iliac artery aneurysm was successfully treated with endovascular repair. Six months later, he developed coronary artery involvement with spontaneous dissection of left anterior descending artery diagnosed on coronary angiogram which was managed conservatively. At 6-year follow-up, he remains clinically asymptomatic and continues with regular surveillance imaging. Iliac arterial fibromuscular dysplasia is uncommon and clinical presentation with a complication such as a deep vein thrombosis is atypical.

Frequency and causes of delayed diagnosis of visceral artery pseudoaneurysms with CT: Lessons learned

Objective

Visceral artery pseudoaneurysms (VAPA) are associated with a high morbidity and mortality, but sometimes are missed in initial computed tomography (CT) examinations. The aims of this study were to determine the frequency and causes of misdiagnoses of VAPA with CT.

Materials and Methods

We retrospectively identified 77 patients with VAPA in our database who underwent contrast-enhanced CT. The frequency of delayed diagnosis was determined and the reasons were noted. We identified the etiology of VAPA, measured size, and noted the affected vessels.

Results

Forty-five of the 77 patients (58 %) had a delayed diagnosis of VAPA. There was no difference in the rate of missed VAPA in symptomatic compared to asymptomatic patients (p = 0.255). The majority of VAPA were associated with previous surgery or interventions (n = 48/62 %). The major affected vessel was the hepatic (n = 31) followed by the splenic artery (n = 17). The main reasons for misdiagnosis were a missed arterial phase in CT (n = 16/36 %), artifacts masking the aneurysm (n = 9/20 %), overlooked pseudoaneurysm (n = 19/42 %), and misinterpretation by attending radiologists (n = 1/2 %). Missed VAPA were smaller (median 8 mm) than those VAPA that were initially diagnosed (median 13 mm, p < 0.01), but occurred with a similar frequency in larger and smaller visceral arteries (p = 0.601).

Conclusions

Our study showed that 58 % of VAPA were diagnosed with delay, with the following four reasons for misdiagnosis: Lack of an arterial contrast phase in CT, no techniques for artifact reduction, and lack of awareness of the radiologists. Avoiding delayed diagnosis will most probably improve outcome of patients with VAPA.

Metachronous rupture of a residual pancreaticoduodenal aneurysm after release of the median arcuate ligament: a case report

Background

Multiple pancreaticoduodenal artery aneurysms in association with median arcuate ligament syndrome (MALS) are relatively rare. A treatment option, such as a median arcuate ligament (MAL) release or embolization of the aneurysms, should be considered in such cases, but the treatment criteria remain unclear.

Case report

A 75-year-old man was transferred to our hospital because of a ruptured pancreaticoduodenal aneurysm. Emergency angiography showed stenosis of the root of the celiac axis (CA), a ruptured aneurysm of the posterior inferior pancreaticoduodenal artery (PIPDA), and an unruptured aneurysm of the anterior inferior pancreaticoduodenal artery (AIPDA). Coil embolization of the PIPDA was performed. Five days after embolization, the gallbladder became necrotic due to decreased blood flow in the CA region, and an emergency operation was performed. We performed a cholecystectomy and released the MAL to normalize the blood flow of the CA region. However, the patient died on postoperative day 8 because of rupture of the untreated aneurysm of the AIPDA.

Conclusions

This is the first report of metachronous ruptures of multiple pancreaticoduodenal aneurysms due to MALS, even after a MAL release. Although rare, a residual aneurysm in the pancreatic head region may need to be embolized quickly.

Segmental arterial mediolysis (SAM): Systematic review and analysis of 143 cases

Segmental arterial mediolysis (SAM) is a rare but serious nonatherosclerotic, noninflammatory vasculopathy of unknown etiology that often results in dissection, aneurysm, occlusion, or stenosis of, primarily, the abdominal arteries. Current literature lacks consensus on diagnostic criteria and management options for SAM. This review summarizes 143 cases and aims to advance appropriate recognition and management of SAM. Literature review of all relevant SAM case studies from 2005 to 2018 yielded 126 individual SAM cases from 66 reports. We identified 17 additional SAM cases from our center, bringing our analysis to 143 patients. Patients with SAM were most commonly men (68%) in their 60s. Hypertension (43%), tobacco use (12%), and hyperlipidemia (12%) were common comorbidities. Abdominal pain (80%) and intraabdominal bleeding (50%) were the most common presenting symptoms. Computed tomography was the most frequently used imaging method (78%), and histology was available in 44% of cases. The most commonly affected vessels were the superior mesenteric (53%), hepatic (45%), celiac (36%), renal (26%), and splenic (25%) arteries with aneurysm (76%), dissection (61%), and arterial rupture (46%). Treatments included coil embolization (28%), abdominal organ surgery (24%), open arterial repair (21%), and medical management (20%). Case-specific treatment modalities yielded symptom relief in the vast majority (91%) of patients, with a mortality rate of 7%.

Segmental Arterial Mediolysis: A Case Study and Review of the Literature in Accurate Diagnosis and Management

Segmental arterial mediolysis (SAM) is a rare noninflammatory, nonarteriosclerotic arteriopathy of an unknown etiology. It most commonly affects the medium-sized vessels of the abdomen and is characterized by the disruption of the arterial medial layer. Although histological confirmation remains the gold standard in diagnosis, the use of computed tomography angiography (CTA) has greatly aided the diagnosis and surveillance of SAM. Given its rarity and angiographic similarities to other vasculopathies, the diagnosis of SAM can be challenging and is often missed. We describe the case of a 46-year-old male patient who presented to our institution with abdominal pain and multiple foci of intra-abdominal arterial dissections on CTA. We report the acute management via endovascular intervention and review the literature with respect to the diagnosis and management of this rare condition. SAM remains an uncommon yet significant disease process requiring prompt and accurate diagnosis. Initiation of immediate treatment is crucial, given the knowledge gap about its natural progression.

Case 270: Spontaneous Coronary Artery Dissection Associated with Fibromuscular Dysplasia

HistoryA 54-year-old woman presented with typical chest pain during physical training at the gym. She had a history of hypertension controlled with hydrochlorothiazide, without any other cardiovascular risk factor and with neither personal nor family history of ischemic heart disease. She was postmenopausal and had a long-standing history of migraine headaches without hormonal or drug therapy. The patient had no history of clinically important thoracic trauma or invasive chest interventions. Initial electrocardiography (ECG) showed signs of ongoing anterior ST segment elevation myocardial infarction, and emergent coronary angiography with angioplasty and intravascular US were performed. Maximal level of high-sensitive T troponins was 820 ng/L (normal, <13 ng/L), while echocardiography showed a normal left ventricular ejection fraction, with no apparent regional wall motion abnormalities. General physical examination findings were unremarkable, excluding ligamentous hyperlaxity and joint instability. C-reactive protein, rheumatoid factor, antinuclear antibody, cytoplasmic antineutrophil cytoplasmic antibody, and angiotensin-converting enzyme blood test results were negative. For further evaluation, arterial phase ECG-synchronized CT angiography from the skull base to the pubis symphysis was performed.

Coronary Artery Involvement in Segmental Arterial Mediolysis: A Case Report

Segmental arterial mediolysis (SAM) is an increasingly recognized disorder affecting small- to medium-sized muscular arteries. A patient with SAM involving the visceral arteries who was also found to have multivessel coronary artery involvement is described. The patient underwent a battery of biochemical, imaging, and genetic tests to exclude other vasculitides and connective tissue disorders. The aim is to shed light on the potential for SAM to affect the coronary arteries and recommend screening of the coronary arteries of patients with SAM. © RSNA, 2019.

Segmental arterial mediolysis

This article reports the case of a 51-year-old woman in whom brain MRI to follow up multiple sclerosis incidentally discovered an intramural hematoma in the extracranial internal carotid artery. MR angiography of the supra-aortic trunks and CT angiography of the aorta showed arterial dilations, aneurysms, dissections, and intramural hematomas in the internal carotid arteries, vertebral arteries, and arteries in the splanchnic territory. These findings raised suspicion of segmental arterial mediolysis. After 6 months of treatment with antiplatelet drugs, the arterial involvement resolved. Segmental arterial mediolysis is an uncommon disease; low clinical suspicion and radiologists' lack of knowledge about this entity mean that it can go undetected or be confused with other vasculitides. This report describes the most relevant pathophysiological findings and correlates them with the imaging findings.

Segmental Arterial Mediolysis with Preceding Symptoms Resembling Viral Infection Hampers the Differentiation from Polyarteritis Nodosa

A middle-aged man presented with a fever, arthralgia, gastrointestinal symptoms, headache, and rash. After two weeks, the patient suddenly complained of severe abdominal pain, and computed tomography revealed aneurysms in the hepatic and splenic arteries, which increased in size progressively. Given the elevated levels of inflammatory markers and orchitis, polyarteritis nodosa (PN) was initially suspected. Catheter embolization for the ruptured hepatic aneurysm and splenectomy for the large splenic ones were performed, and the pathological finding was consistent with segmental arterial mediolysis (SAM). Changes in inflammatory marker levels and aneurysmal size are also informative to differentiate SAM from PN.

Have You Seen SAM?

Introduction

Segmental arterial mediolysis (SAM) is a rare, non-atherosclerotic, non-inflammatory vascular disease mostly affecting medium to large sized abdominal arteries which may cause aneurysms, stenosis, and haemorrhage.

Report

A case is reported of a patient with SAM affecting the renal arteries bilaterally, where the diagnosis was made by excluding other inflammatory, immunological, and infectious mimickers.

Discussion

As SAM carries a significant mortality and morbidity from end organ ischaemia, infarction, or haemorrhage, it should be considered in any patient presenting with abdominal pain.

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Segmental arterial mediolysis (SAM) should be considered in a patient presenting with acute severe abdominal pain because of the high mortality risk secondary to haemorrhage.

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The mechanism of aneurysms, stenoses, and haemorrhage is thought to involve disruption of the arterial media.

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SAM can be differentiated from its other mimickers by its clinical, laboratory, and radiological findings.

Case of Segmental Arterial Mediolysis

Segmental arterial mediolysis (SAM) is a rare, non-inflammatory, vascular condition that predominantly affects medium-sized to large-sized abdominal arteries and can present with haemorrhage into the abdominal cavity. We report the case of a patient with SAM of the coeliac, splenic, renal and gastroduodenal arteries in whom endovascular coil embolisation was successfully used to treat a bleeding gastroduodenal artery pseudoaneurysm.

Segmental Arterial Mediolysis: Abdominal Imaging of and Disease Course in 111 Patients

OBJECTIVE

The purpose of this study is to identify the imaging characteristics of segmental arterial mediolysis (SAM) at presentation and establish the longitudinal course of disease.

MATERIALS AND METHODS

We retrospectively identified patients with SAM at a single institution from 2000 through 2015. Diagnosis was based on published guidelines with multidisciplinary consensus. Imaging studies obtained at initial evaluation were reviewed to evaluate imaging findings and vascular territory distribution. All subsequent follow-up imaging studies were reviewed to assess for progression, stability, or regression.

RESULTS

We identified 111 patients (79 men and 32 women; median age, 51 years) who met the diagnostic criteria for SAM. Abdominal pain was the most common presentation (74%), followed by flank pain (21%). SAM most commonly affected the renal arteries (47%), superior mesenteric artery (46%), celiac trunk (46%), hepatic artery (23%), iliac arteries (18%), and splenic artery (14%). The most common imaging findings were dissection (86%), aneurysm (57%), beading or webs (28%), occlusion (19%), and a rind or wall thickening (15%). The 247 available follow-up imaging studies for 97 patients (median follow-up, 12 months) showed progression in 19 patients (20%), with either stability or regression observed in the remaining patients.

CONCLUSION

SAM most commonly affects the renal arteries, superior mesenteric artery, and celiac artery. Dissections and aneurysms are the most common imaging findings. Follow-up imaging studies show stability or regression in most patients.

Potentially stress-induced acute splanchnic segmental arterial mediolysis with a favorable spontaneous outcome

A 62-year-old woman presented with hemithoracic anesthesia and acute abdominal pain following a violent psychological stress. Magnetic resonance imaging showed a thoracic hematoma with arachnoiditis of the spinal cord. Tomography revealed a typical aspect of segmental arterial mediolysis with multiple aneurysms and stenoses of the splanchnic arteries, confirmed by abdominal arteriography. There was no argument for hereditary, traumatic, atherosclerotic, infectious, or inflammatory arterial disease. Segmental arterial mediolysis was diagnosed on the basis of the radiologic data and probably involved both medullary and splanchnic arteries. The patient spontaneously recovered and was in good health 18 months later.

A Case of Segmental Arterial Mediolysis Presenting as Mucosal Gastric Hematoma

Background

Although segmental arterial mediolysis (SAM) has been increasingly recognized as arteriopathy and there are some case reports about SAM, it is still very rare. It is characterized clinically by aneurysm, dissection, stenosis, and occlusion within splanchnic arterial branches, causing intra-abdominal hemorrhage or bowel ischemia. Mortality is as high as 50% in acute events.

Case Presentation

A 51-year-old man was referred to our hospital with hematemesis. Gastroscopy revealed a submucosal-like tumor on the posterior wall of gastric angle with ulceration. Computed tomography indicated a tumor measuring 65 × 50 mm in the stomach, which was suspected to have invaded into the pancreas. Significant hematemesis recurred; the patient developed shock and underwent emergency distal gastrectomy, distal pancreatectomy, and splenectomy. The pathology and the clinical course were compatible with SAM splenic artery rupture causing retroperitoneal hemorrhage that penetrated into the stomach. After that surgery, aneurysm of common hepatic artery ruptured and coil embolization was performed.

Conclusion

SAM is an important cause of intra-abdominal or retroperitoneal hemorrhage in patients without underlying disease. SAM typically presents as intra-abdominal hemorrhage, but, in this case, the retroperitoneal hemorrhage penetrated into the stomach and it looked like a submucosal tumor.

Spontaneous isolated dissection of the superior mesenteric artery and aneurysm formation resulting from segmental arterial mediolysis: a case report

Background

Spontaneous isolated dissection of the superior mesenteric artery (SMA) can lead to bowel ischemia, aneurysm rupture, or even death. Studies have suggested that mechanical or hemodynamic stress on the vascular wall of the SMA may be a contributor, but its pathogenesis is unclear.

Case presentation

A 57-year-old Japanese man with a history of untreated hypertension and hyperuricemia was admitted to our hospital with the sudden onset of severe epigastric pain. Laboratory findings showed elevated white blood cell count and C-reactive protein, and contrast-enhanced computed tomography (CT) of the abdomen demonstrated arterial dissection with luminal stenosis and aneurysm formation at the distal portion of the SMA after the branching of the jejunal artery, and intravenous nicardipine was administered. The patient’s epigastric pain resolved spontaneously but recurred on day 6 of his hospital stay. Contrast-enhanced abdominal CT revealed an enlarged aneurysm with wall thinning. Because of the risk of aneurysm rupture, the decision was made to perform aneurysmectomy and bowel resection on day 6. Histologic examinations revealed two separate dissecting lesions: one latent and the other resulting in aneurysm formation. Both lesions showed characteristics of segmental arterial mediolysis (SAM) with lack of arterial media, absence of internal and external elastic laminae and intimal proliferation.

Conclusions

Histologic findings in the present case suggest that mechanical or hemodynamic stress on the vascular wall and SAM-related vascular vulnerability may concomitantly contribute to the onset of isolated SMA dissection.

Segmental Arterial Mediolysis: An Unusual Case Mistaken to be a Strangulated Hernia

INTRODUCTION

Segmental arterial mediolysis (SAM) is a rare nonatherosclerotic, noninflammatory vasculopathy causing arterial wall necrosis that leads to strictures, dissections, and aneurysms, particularly in medium-sized abdominal arteries. Awareness of SAM is important because, unlike vasculitides, immunosuppressive treatment may worsen the disease process.

CASE

A 58-year-old man with multiple medical comorbidities presented with acute epigastric pain and a right incarcerated inguinal hernia that was interpreted as showing bowel strangulation on computed tomography. The hernia was unable to be reduced in the emergency department, so the patient was taken for open reduction by the surgical service. Intraoperatively, he was noted to have a ruptured superior mesenteric artery aneurysm. Conventional angiography demonstrated a bead-like appearance of several jejunal branches of the superior mesenteric artery, raising concern for a vasculitis. His hospital course included rheumatologic consultation, and initial recommendations were to start immunosuppressive therapy for treatment of polyarteritis nodosa. Further testing demonstrated normal antinuclear antibody, antineutrophil cytoplasmic antibodies, and complement levels. Due to a lack of systemic symptoms or signs and otherwise unremarkable laboratory evaluation, the patient ultimately was diagnosed with SAM and immunosuppressive therapy was halted.

DISCUSSION

Unexplained medium arterial stenosis, dissection, aneurysm, and hemorrhage should raise suspicion for possible SAM. The initial management approach should focus on treatment of the acute hemorrhage, usually involving endovascular stenting or coil embolization. Unlike vasculitides, SAM does not benefit from, and may actually be harmed by, immunosuppressive therapy.

CONCLUSIONS

Clinicians involved in the longitudinal care of emergency department patients should be aware of this rare clinical entity in order to initiate appropriate treatment.

Imaging and clinical findings in segmental arterial mediolysis (SAM)

Segmental arterial mediolysis (SAM) is an uncommon, non-atherosclerotic, non-inflammatory arteriopathy that tends to affect the medium-sized splanchnic branches of the aorta along with renal, carotid, cerebral, and coronary arteries. The clinical presentation ranges from asymptomatic to severe, life-threatening intra-abdominal hemorrhage and shock. SAM overlaps clinically and radiologically with other inflammatory vasculitides. This article describes the pathologic-radiologic correlation, imaging findings, and the management of the disease. Radiologists should be familiar with this disease entity as imaging plays a crucial role in the diagnosis.