Idiopathic IgG4-negative perivascular fibrosis with extensive thoracic aortic, coronary artery, and supra-aortic branch involvement: A case report

Abstract

Perivascular fibrosis is an uncommon fibroinflammatory disorder characterized by circumferential soft-tissue thickening surrounding the aorta and its major branches. Involvement of the thoracic region and supra-aortic branches is less common, potentially leading to imaging studies that can resemble large-vessel vasculitis, inflammatory pseudoaneurysms, or lymphoproliferative disorders. In this report, we discuss a case involving a 55-year-old male with long-standing retroperitoneal fibrosis and chronic occlusion of the infrarenal aorta. The condition also exhibited extensive involvement of the thoracic aorta, coronary artery, and supra-aortic branches. Coronary artery stenosis that resulted in ST-elevation myocardial infarction demanding percutaneous intervention and surgical revascularization was a component of disease progression over 20-year follow-up. This case highlights the essential role of multimodal imaging techniques in differentiating perivascular fibrosis from primary large-vessel vasculitis and malignancies, particularly in patients who are IgG4-negative with considerable thoracic involvement.

Introduction

Perivascular fibrosis is an uncommon fibroinflammatory condition characterized by the circumferential thickening of soft tissue surrounding the aorta and its primary branches [1,2]. Most cases involve infrarenal abdominal aortic retroperitoneal fibrosis, with potential for extension to adjacent retroperitoneal structures [3,4]. In recent years, a significant number of cases previously classified as idiopathic have been reclassified under immunoglobulin G4–related disease (IgG4-RD) [5,6]. This condition is characterized by dense lymphoplasmacytic inflammation and a storiform pattern of fibrosis [1,6]. Nevertheless, IgG4-negative forms remain recognized as a distinctive and diagnostically challenging category [7]. Thoracic aortic and supra-aortic branch involvement is relatively rare and may radiologically mimic conditions such as large-vessel vasculitis, inflammatory pseudoaneurysms, atherosclerotic diseases, or lymphoproliferative disorders [2]. In contrast to primary aortitis, which is characterized by transmural inflammation of the arterial wall, perivascular fibrosis mainly influences the adventitial layer and surrounding soft tissues of the aorta [2,8]. We present a case of extensive IgG4-negative idiopathic perivascular fibrosis with unusual involvement of the coronary arteries, thoracic aorta, and supra-aortic branches, emphasizing the value of multimodal cross-sectional imaging for accurate diagnosis, surveillance, and clinical management.

Case presentation

A 55-year-old male with a long-standing diagnosis of idiopathic retroperitoneal fibrosis has been under continuous assessment for multilevel large-vessel pathology. Since adolescence, he reported experiencing exertional claudication, characterized by lower extremity numbness and burning sensations after prolonged physical activity. Transient systemic symptoms included fatigue, fever, chills, and elevated liver function tests. Cross-sectional imaging during this time unexpectedly revealed circumferential soft tissue thickening around the abdominal aorta, raising suspicion of lymphoma. In 2003, at the age of 33, he was found to have occlusion of his infrarenal abdominal aorta with collateral circulation suggesting this was a chronic change (Fig. 1). Retroperitoneal fibrosis was diagnosed based on the stereotypical imaging findings and persistent involvement without need for tissue biopsy. Surgical intervention was postponed due to the assessment that vascular surgery posed excessive risks compared to its potential advantages. A non-contrast chest CT in 2003 also showed calcifications in the right coronary artery and distal descending aorta, an unexpected finding for a patient this age (Fig. 1A).

Fig. 1.

Montage of imaging findings at initial diagnosis in 2003. (A) Axial non-contrast CT demonstrates focal coronary artery calcification (arrow) and additional calcification in the descending thoracic aorta (arrow). (B) Axial contrast-enhanced CT at the thoracic inlet shows circumferential soft tissue encasing the brachiocephalic artery (arrow). (C) Axial contrast-enhanced CT demonstrates circumferential periaortic soft tissue surrounding the thoracic aorta and calcification (arrow) without evidence of dissection. (D) Axial contrast-enhanced CT at the level of the renal arteries shows circumferential soft tissue encasing the abdominal aorta (arrow) with mild luminal narrowing. (E) Axial contrast-enhanced CT of the infrarenal abdominal aorta demonstrates near-complete occlusion due to circumferential retroperitoneal fibrotic encasement (arrow). (F-G) Sagittal and axial reformatted MR angiography images showing periaortic and brachiocephalic artery wall thickening due to fibrosis (arrows). (H) Digital subtraction angiography of the abdominal aorta demonstrates severe stenosis with near-complete occlusion of the infrarenal aorta (arrows), accompanied by extensive collateral circulation, consistent with chronic large-vessel obstruction.

In February 2020, the patient experienced right lower extremity swelling, resulting from deep venous thrombosis extending from the right external iliac vein to the popliteal vein, which was treated with tissue plasminogen activator (tPA). During this hospitalization, a CT angiogram of the abdominal aorta (Fig. 3A–D) and both lower extremities indicated “significant irregular narrowing of the visualized aorta along with proximal bilateral common iliac vessels due to encasement by prominent surrounding soft tissue density.” The imaging also demonstrated widely patent bilateral lower extremity arterial circulation and numerous compensatory venous collaterals throughout the abdomen, pelvis, and lower extremities. The patient had complete occlusion of the infrarenal abdominal aorta and inferior vena cava (IVC). He was started on long-term anticoagulation. Serum IgG4 levels were found to be within normal range on multiple occasions. Rheumatological testing revealed positive anti-Ro (SSA) and anti-La (SSB) antibodies with elevated antinuclear antibody (ANA) titer, though no evidence of other organ involvement was identified. Testing for antiphospholipid antibodies, ANCA, and other connective tissue disease markers was negative.

Fig. 3.

Imaging of disease of the abdominal aorta in 2020-2024. (A-D) Axial and Coronal contrast-enhanced CT images of the abdominal aorta demonstrate circumferential periaortic soft tissue thickening with calcification. Long arrows identify the superior mesenteric, left renal, and inferior mesenteric arteries. Note the absence of the inferior vena cava due to chronic obstruction caused by retroperitoneal fibrosis. (E, F) Axial non-contrast T1-weighted MR image (E) shows bulky periaortic soft tissue (arrows) with intermediate-to-high signal and signal voids (calcifications). Axial post-contrast (venous phase) T1-weighted MR images (F) show heterogeneous enhancement (active inflammation) intermixed with non-enhancing components (fibrosis) and signal voids (calcifications). This causes subtotal occlusion of the distal aorta. The inferior vena cava is chronically occluded and is not seen. (G) Coronal T2-weighted MRI of the abdomen demonstrates circumferential low-to-intermediate T2 signal periaortic soft tissue encasing the infrarenal abdominal aorta, bilateral common iliac arteries, and proximal renal arteries (arrows). (H) Coronal maximum intensity projection (MIP) contrast-enhanced MR angiography in the arterial phase shows marked infrarenal abdominal aortic and common iliac artery narrowing (arrow) with extensive serpiginous collateral vessels throughout the retroperitoneum (arrowheads), compatible with chronic aortoiliac occlusive disease.

Magnetic resonance angiography (MRA) of the abdomen and pelvis demonstrated T2 hypointense retroperitoneal soft tissue enveloping the abdominal aorta from the diaphragmatic hiatus to its bifurcation (Fig. 3E–H). This encasing tissue measured up to 4.5 × 3.0 cm at the level of the renal arteries and showed peripheral enhancement after contrast administration. There was near complete occlusion of both the infrarenal abdominal aorta and proximal common iliac arteries. Once again, the IVC was chronically occluded with significant venous collateralization. Although encased, the proximal superior mesenteric artery and renal arteries remained patent. Longitudinal imaging over several years indicated an overall stability in both the abdominal perivascular soft tissue and associated vascular stenoses, with no evidence of progression.

Follow-up cross-sectional imaging in 2024 revealed that the fibroinflammatory process in the thoracic region had progressed since 2003. A chest CT angiogram showed asymmetric circumferential thickening of soft tissue surrounding the distal descending thoracic aorta, with a maximum thickness of 1.2 cm and coarse internal calcifications (Fig. 2E–F). Additionally, similar perivascular soft tissue was observed along the brachiocephalic (innominate) artery, extending towards the origins of both the right common carotid and right vertebral arteries (Fig. 2A–D). The brachiocephalic artery contained a patent stent, placed at an outside institution. Moderate stenosis in the brachiocephalic artery distal to the stent was noted, alongside small broad-based pseudoaneurysms measuring approximately 4–5 mm at the bifurcation of the right common carotid and right vertebral arteries (Fig. 2C).

Fig. 2.

Imaging of disease of the brachiocephalic artery in 2024. (A) Curved planar reformatted CT angiography (CTA) images of the aortic arch demonstrate a stent within the proximal brachiocephalic artery (arrows) with preserved contrast opacification of the stented lumen. Surrounding partially calcified perivascular soft tissue thickening is present. (B) Axial CTA image showing the stented brachiocephalic artery en face (arrows) demonstrates perivascular soft tissue encasement with irregular calcifications. (C) Axial post-contrast T1-weighted image showing anatomic variation with origin of the right vertebral artery arising at the bifurcation of the right common carotid and subclavian arteries with a small broad-based saccular pseudoaneurysm (long arrow). (D) Coronal T2-weighted MR image demonstrates circumferential low signal intensity from the metal stent with heterogeneous T2 perivascular soft tissue surrounding the brachiocephalic artery (arrows) compatible with chronic fibrosis and calcifications. (E-F) Axial (E) and Coronal (F) contrast-enhanced CT demonstrates circumferential partially calcified periaortic soft tissue encasing the descending thoracic aorta (arrows). (G-H) Axial pre (H) and post (G) T1-weighted MR images demonstrate circumferential intermediate-to-high T1 signal periaortic soft tissue with signal voids (calcifications) encasing the descending thoracic aorta (arrows), with enhancement.

The patient developed chest pain in 2023 and was found to have an ST-elevation myocardial infarction requiring immediate invasive coronary angiography (Fig. 5A–E). The left main coronary artery was occluded with collateral circulation via the posterior descending artery (PDA) giving rise to retrograde flow in the left circumflex and left anterior descending (LAD) arteries. Percutaneous coronary intervention was performed with successful cannulation of the left main followed by ballooning and stenting of the left main, proximal left circumflex, and large first obtuse marginal branch. The proximal LAD was completely occluded and could not be cannulated. There was mild disease in the mid-right coronary artery with good flow.

Fig. 5.

Conventional coronary angiography for management of ST-elevation myocardial infarction (2023). Cardiac MR imaging prior to coronary artery bypass grafting to assess for viability (2023). (A) Subtotal occlusion of the left main coronary artery (arrow). No opacification of the downstream LAD or left circumflex arteries. (B) High-grade stenosis of the left main (arrow) crossed by a guidewire with opacification of the diseased first obtuse marginal artery (arrowhead). (C) Mild stenosis of the right coronary artery (arrow). Collateral circulation via the posterior descending artery with retrograde flow into the left circumflex artery (long arrows) and distal LAD (arrowhead). (D-E) Opening of the left main, left circumflex, and large obtuse marginal branches with balloon and stent. No opacification of the LAD. (F) 3D post-contrast delayed-enhancement T1-weighted MR image showing subendocardial delayed-enhancement in a large area of the septum, apex, and lateral wall of the left ventricle (arrows). (G-H) 2D phase-sensitive inversion recovery delayed-enhancement MR images showing subendocardial delayed-enhancement in the anterior wall, septum, apex, and lateral wall of the left ventricle (arrows). There is involvement of less than 50% of the myocardial wall thickness, suggesting viable myocardium.

Subsequent cardiac MR imaging was performed to evaluate myocardial viability prior to coronary artery bypass grafting (CABG). Subendocardial delayed enhancement involving less than 50% of the myocardial wall thickness indicated viable myocardium in the LAD and left circumflex distributions. The patient underwent successful single-vessel CABG with a left internal mammary artery graft to the distal LAD (Fig. 5F–H).

Follow-up coronary CT angiography in 2024 demonstrated predominantly noncalcified soft tissue encasing and chronically occluding the proximal LAD (Fig. 4D–F). The right coronary artery had non-flow-limiting stenosis in the mid-segment. The LIMA graft and left circumflex/OM1 stent were patent. The degree of coronary artery calcification, as well as distal descending aortic soft tissue encasement, had increased since the 2003 chest CT (Fig. 4A–B). Echocardiography (not shown) revealed an ejection fraction of 45-50% with chronic systolic heart failure due to ischemic cardiomyopathy. His idiopathic perivascular fibrosis was managed by a team including a rheumatologist, cardiologist, neurologist, vascular surgeon and multiple radiologists. At his most recent rheumatology and cardiology visits, his vascular disease was considered stable on optimal medical management with a beta-blocker, an angiotensin receptor blocker, and a diuretic with no indication for immunosuppressive therapies.

Fig. 4.

Imaging of disease of the coronary arteries. (A) Axial non-contrast CT (2003) demonstrates focal right coronary artery calcification (arrow). (B) Axial non-contrast CT (2024) shows progression of coronary artery calcification compared with 2003 with additional calcification in the descending thoracic aorta (arrowhead). Also note the placement of an interatrial septal occluder device (arrowhead). (C) Axial non-contrast CT (2024) demonstrates a left main, left circumflex, and first obtuse marginal coronary artery stent (arrow). There is also a partially seen left atrial appendage clip (arrowhead). (D) Curved planar reformatted CCTA of the left anterior descending (LAD) artery demonstrates predominantly noncalcified soft tissue thickening of the vessel wall (arrows) with complete occlusion of the proximal segment. (E) Curved planar reformatted CCTA of the LAD demonstrates a patent left internal mammary artery (LIMA) graft anastomosed to the distal LAD. Soft tissue wall thickening is redemonstrated. (F) Curved planar reformatted CCTA showing a patent stent (arrow) extending from the left main into the large first obtuse marginal branch, placed in February 2023 following ST-elevation myocardial infarction.

Discussion

Perivascular fibrosis, encompassed within the spectrum of chronic periaortitis and retroperitoneal fibrosis, is characterized by circumferential soft-tissue thickening primarily involving the adventitia and periadventitial tissues, in contrast to large-vessel vasculitis such as Takayasu arteritis and giant cell arteritis, which demonstrate transmural wall inflammation [1,8]. In our patient, imaging revealed circumferential, bulky soft tissue around the involved vessels without transmural thickening, favoring perivascular fibrosis over primary vasculitis.

Another important differential consideration is lymphoma. Most types of lymphoma typically present as an enhancing nodal mass causing mass effect, such as anterior displacement of the aorta [3]. The nodal mass is more frequently homogeneous, surrounds but does not occlude the vessels involved, and develops over months rather than years. On the other hand, perivascular fibrosis typically shows uniform encasement around the vessels with a heterogeneous soft tissue appearance and multiple calcifications. Vessels are frequently stenotic or occluded and the disease is chronic. Longitudinal stability of abdominal imaging findings over many years in our patient was strong evidence against malignancy.

In a substantial patient cohort analysis involving chronic periaortitis patients, approximately one-third exhibited involvement of the thoracic aorta or epiaortic branches [2]. However, extensive encasement of supra-aortic branches leading to stenosis and pseudoaneurysm formation remains relatively rare in the available literature. The current case illustrates extensive multilevel involvement throughout the aorta with involvement of the coronary arteries, brachiocephalic artery, proximal right common carotid and vertebral arteries, proximal mesenteric and renal arteries, as well as chronic occlusion of the infrarenal aorta and inferior vena cava. Coronary artery involvement in the setting of idiopathic retroperitoneal fibrosis is exceptionally rare. Prior reports have described pericoronary soft tissue proliferation in idiopathic retroperitoneal fibrosis without hemodynamically significant stenosis [9], as well as a characteristic “mistletoe sign” on cardiac MR and coronary CT angiography representing pericoronary fibrotic tissue proliferations [10]. While coronary periarteritis has been documented predominantly in IgG4-positive cases [11], our case demonstrates that this life-threatening complication leading to ST-elevation myocardial infarction and surgical revascularization may also occur in the IgG4-negative spectrum of perivascular fibrosis.

CT angiography facilitated detailed evaluation of vascular encasement, luminal narrowing, collateral circulation, and pseudoaneurysm formation [1,5]. We found the soft tissue thickening to be bulky and mass-like with scattered calcifications. MRI provided complementary tissue characterization, demonstrating T2 hypointensity consistent with calcified fibrotic tissue, and T1 intermediate to high signal intensity, with variable enhancement suggesting active-on-chronic inflammation [3]. Longitudinal imaging conducted over several years in our patient confirmed overall stability of abdominal disease despite continued perivascular soft tissue enhancement. However, disease within the chest progressed over the more than 20-year follow-up period, reinforcing the notion of a chronic condition with multiple acute exacerbations requiring close management and follow-up.

The correlation between IgG4-related disease (IgG4-RD) and chronic periaortitis is widely acknowledged; up to 50% of idiopathic retroperitoneal fibrosis cases reveal histopathological characteristics consistent with IgG4-RD [1,5]. Patients with IgG4-related periaortitis typically demonstrate multi-organ involvement with elevated serum IgG4 levels [1,8], whereas IgG4-negative forms may lack systemic symptoms entirely [5,8]. Thoracic manifestations have been documented in both groups [2]. In our patient, persistently normal serum IgG4 levels with no other organ involvement confirmed a diagnosis of IgG4-negative idiopathic perivascular fibrosis, reinforcing that a negative IgG4 result does not exclude this condition.

Conclusion

Idiopathic perivascular fibrosis can exhibit significant multilevel involvement that extends beyond the abdominal aorta, sometimes affecting thoracic and supra-aortic branches. Identifying the distinctive imaging characteristics specifically, bulky, partially calcified, circumferential vascular encasement with associated stenosis or occlusion is essential for differentiating this condition from primary large-vessel vasculitis and lymphoproliferative disorders. It is important to note that normal serum IgG4 levels do not exclude perivascular fibrosis. Multimodal cross-sectional imaging is vital for diagnosis, ongoing evaluation, and guiding treatment decisions.

Ethics statement

This study was reviewed by the Institutional Review Board of the University of Utah.

Data availability

No datasets were generated or analyzed for this study. All clinical and imaging information supporting the findings of this case report are included within the article. Additional details are not publicly available in order to protect patient privacy.

Patient consent

Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal upon request.