Arteriolymphatic fistula between the thoracic duct and lumbar artery pseudoaneurysm after open abdominal aortic aneurysm repair

Abstract

Arteriolymphatic fistulas are extremely rare. We describe a 76-year-old man who developed a fistulous communication between the thoracic duct and a lumbar artery pseudoaneurysm after open abdominal aortic aneurysm repair. Only seven similar cases have been reported previously. Because the patient was asymptomatic, conservative management was selected, resulting in spontaneous thrombosis and complete resolution. This case suggests that careful observation may be an appropriate management strategy for selected postoperative arteriolymphatic fistulas detected on follow-up imaging.

Arteriolymphatic fistulas are an uncommon pathological communication between the arterial and lymphatic systems. Most reported cases have been iatrogenic or traumatic. Because of their rarity, the underlying mechanisms, diagnostic features, and optimal management strategies remain poorly defined. Here, we describe a rare postoperative case of a fistulous communication between the thoracic duct and a lumbar artery pseudoaneurysm detected after open abdominal aortic aneurysm (AAA) repair.

Case report

A 76-year-old man was incidentally diagnosed with an asymptomatic infrarenal AAA (diameter of 51 mm). Preoperative coronary angiography revealed severe three-vessel disease, and coronary artery bypass grafting was performed the day before AAA repair. Although endovascular aneurysm repair would generally have been preferable, the aneurysm was located immediately below the renal arteries and considered anatomically unsuitable for endovascular aneurysm repair. Therefore, open repair was selected. Open AAA repair was performed through a midline laparotomy, and the infrarenal aorta was replaced with a bifurcated graft. The L2 lumbar artery was oversewn from within the aneurysm sac using 3-0 polypropylene mattress sutures.

Although not mandated by international guidelines, contrast-enhanced computed tomography (CT) was performed on postoperative day 14 according to our institutional protocol for routine early surveillance. In this patient, postoperative imaging was performed slightly later than usual because coronary artery bypass grafting had been performed the day before aneurysm repair. The patient remained asymptomatic. The examination revealed a pseudoaneurysm arising from the left L2 lumbar artery (9.7 × 15.2 mm) with a fistulous communication to the thoracic duct (Fig 1). Three-dimensional reconstructed CT scan clearly demonstrated the spatial relationship between the pseudoaneurysm and the thoracic duct (Fig 2, A) and the lymphatic drainage pathway into the left venous angle (Fig 2, B). There were no clinical or laboratory findings suggestive of infection. Conservative management with imaging surveillance was selected. Follow-up CT scan on day 47 showed marked regression of the pseudoaneurysm and thoracic duct dilatation (Fig 3, A). At 3 months, complete resolution was confirmed (Fig 3, B). This study was approved by the institutional review board of our institution. Written informed consent was obtained from the patient.

Fig 1.

Contrast-enhanced computed tomography (CT) demonstrating an arteriolymphatic fistula. (A) Axial contrast-enhanced CT image demonstrating a direct fistulous communication between the lumbar artery pseudoaneurysm and an adjacent dilated lymphatic structure. Arrows indicate the pseudoaneurysm lumen and the site of communication, and the arrowhead indicates the dilated lymphatic structure. (B) Sagittal multiplanar reconstructed contrast-enhanced CT image demonstrating continuity between the left L2 lumbar artery (arrow) and the pseudoaneurysm (arrow). (C) Sagittal multiplanar reconstructed contrast-enhanced CT image demonstrating cranial continuation of the dilated lymphatic structure (arrowhead), consistent with the thoracic duct. Multiplanar reconstructed images were used to demonstrate the spatial relationship and sequential continuity between the lumbar artery pseudoaneurysm and the lymphatic system.

Fig 2.

Three-dimensional reconstructed computed tomography (CT) demonstrating the lymphatic drainage pathway. (A) Three-dimensional reconstructed CT image demonstrating the spatial relationship and continuity between the lumbar artery pseudoaneurysm and the adjacent lymphatic structure. The arrow indicates the lumbar artery and pseudoaneurysm, and the arrowhead indicates the lymphatic structure. (B) Three-dimensional reconstructed CT image demonstrating the lymphatic drainage pathway from the cisterna chyli to the left venous angle. The thoracic duct is shown extending cranially before draining into the left subclavian vein and subsequently into the superior vena cava. Note that the left-right orientation is reversed in this image.

Fig 3.

Follow-up computed tomography (CT) images. (A) Contrast-enhanced CT image obtained on postoperative day 47 demonstrating marked decrease of the lumbar artery pseudoaneurysm and decreased dilatation of the thoracic duct. The arrow indicates the residual pseudoaneurysm. (B) Contrast-enhanced CT image obtained 3 months postoperatively demonstrating complete thrombosis of the pseudoaneurysm and disappearance of thoracic duct opacification. The arrow indicates the former location of the pseudoaneurysm, where no residual lesion is identified.

Discussion

Including the present case, our literature search identified eight reported cases of arteriolymphatic fistulas involving the abdominal aorta or its branches (Table). We performed a PubMed search using keywords “arteriolymphatic fistula,” “arteriothoracic duct fistula,” and “arteriocisterna chyli fistula” in English articles. Lumbar artery pseudoaneurysm after open AAA repair is exceedingly rare, and its natural history without a fistulous communication remains poorly defined. Although spontaneous closure of arteriolymphatic fistulas has been observed in several cases,1, 2, 3, 4, 5 nonfistulous pseudoaneurysms rarely resolve spontaneously and often require intervention owing to rupture risks. Our case adds to the literature by demonstrating that a fistula originating from a peripheral branch, such as the lumbar artery, may have a greater propensity for spontaneous resolution compared with those involving the main aortic trunk, likely owing to lower inflow volumes.

Table.

Summary of reported cases of arteriolymphatic fistula

Case	Year	Age/sex	Etiology	Site of fistula	Diagnostic modality	Management	Outcome (follow-up)	Reference
I	1970	35/male	Trauma (gunshot)	Aorto–cisterna chyli	Angiography	Conservative	3 weeks: spontaneous closure	Nguyen LQ et al.
II	1986	65/male	Spontaneous	Aortocisterna chyli	Angiography	Conservative	2 months: asymptomatic	Vlahos L et al.
III	2007	16/female	Iatrogenic	Aortocisterna chyli	Angiography	Stent graft	10 months: occluded	Hwang HS et al.
IV	2013	61/male	Iatrogenic (AAA surgery)	Anastomosis–TD	Contrast CT	Endovascular (coil)	3 months: complete exclusion	Nath AF et al.
V	2016	38/ male	Iatrogenic	Femoral-lymphatic	Ultrasound	Compression	1 week: spontaneous thrombosis	Viswanathan et al.
VI	2018	68/ male	Trauma (MVC)	Aortocisterna chyli	Contrast CT	Thrombin injection	6 days: resolved spontaneously	Freeman BM et al.
VII	2019	42/ male	Spontaneous	TD–aortic branch	CT/angiography	Endovascular (coil, plug)	3 months: embolized	Yamaguchi T et al.
VIII	2026	76/ male	Iatrogenic (AAA surgery)	Lumbar artery–TD	3D CT	Conservative	3 months: resolved	Present case

AAA, Abdominal aortic aneurysm; CT, computed tomography; MVC, motor vehicle collision; TD, thoracic duct.

A review of reported cases suggests a shift in diagnostic approaches (Table). Early reports between 1970 and 2007 (cases I-III) primarily utilized conventional angiography,1, 2, 3 whereas cases reported since 2013 (cases IV-VII) have increasingly relied on contrast-enhanced CT scans.4, 5, 6, 7 Our case follows this recent trend, aligning with the growing role of high-resolution three-dimensional CT scan in providing a clear anatomical roadmap. This imaging modality helps clinicians to confirm the lymphatic nature of the drainage and identify the precise fistula location without the need for invasive catheterization or risky venous interventions.

Specific radiographic features are essential to differentiate this lesion from an arteriovenous fistula. In an arteriovenous fistula, one typically observes early-phase opacification of the inferior vena cava or adjacent veins with rapid clearance. In contrast, our case demonstrated contrast medium entering a discrete tubular structure consistent with the thoracic duct, which followed its known anatomical ascent along the vertebral bodies into the mediastinum. The absence of early filling in the inferior vena cava, combined with the characteristic delayed contrast washout—reflecting the slower flow dynamics of the lymphatic system—supported the diagnosis of an arteriolymphatic communication. Although lymphoscintigraphy is a traditional tool, it was not performed here because the three-dimensional CT scan provided clear evidence of the characteristic cranial trajectory. The combination of these anatomical findings and the slow-flow dynamics, observed noninvasively, was considered sufficient to confirm the diagnosis while avoiding further diagnostic burden in this asymptomatic patient.

At the L1-L2 vertebral level, the thoracic duct and cisterna chyli are located in close proximity to the abdominal aorta and lumbar arteries. During open AAA repair, inadvertent injury to the lumbar artery during ligation from within the aneurysm sac likely contributed to pseudoaneurysm formation. To prevent this rare complication, while maintaining the standard technique of ligation from within the aneurysm sac to avoid venous injury outside the aorta, surgeons should be mindful of the depth of mattress sutures placed on the posterior aortic wall, particularly near the L1-L2 level where lymphatic structures are close.

Open AAA repair often requires extensive dissection of the juxtarenal periaortic region, during which minor lymphatic injury may occur. Despite this, clinically apparent postoperative chylous complications are rare.⁸ This discrepancy is likely related to the reduced lymphatic flow in the early postoperative fasting state, which may allow spontaneous sealing of lymphatic disruptions.⁹ In contrast, lymph flow through the thoracic duct increases substantially after resumption of oral intake, which may explain the delayed presentation of chylous complications.¹⁰ Additionally, the pattern of lymphatic injury may influence healing, because lateral tears are less likely to seal spontaneously than complete transections.¹¹

Conservative management is a reasonable option in carefully selected patients. We define these as patients who are hemodynamically stable, asymptomatic (lacking chylothorax or chylous ascites), have small pseudoaneurysms (<2 cm) without evidence of rapid expansion, and show no clinical or radiological signs of systemic infection. Intervention—such as endovascular embolization, percutaneous thrombin injection, or surgical ligation—should be reserved for symptomatic cases, pseudoaneurysm enlargement, or persistent high-flow shunting. We define the latter as a lack of flow stagnation or progressive dilatation of the lymphatic system or pseudoaneurysm on serial imaging, which may clinically manifest as refractory chylous complications owing to high-pressure arterial inflow overwhelming the lymphatic system.

Spontaneous thrombosis in this case was likely multifactorial, involving diminished arterial inflow through disrupted lumbar collaterals combined with altered flow dynamics, rather than low-resistance lymphatic outflow alone. The unique pressure-flow characteristics of the lymphatic system allow slow drainage without sustaining high-flow circulation.

Conclusions

This report describes a rare arteriolymphatic fistula between the thoracic duct and a lumbar artery pseudoaneurysm following open AAA repair. Conservative management resulted in complete spontaneous resolution. Early postoperative imaging and careful follow-up are essential for identifying this rare complication.

Funding

None.

Disclosures

None.