A bilobed syphilitic thoracoabdominal aortic aneurysm with vertebral erosion and multibranch visceral occlusion

Abstract

A 55-year-old man with serologically confirmed tertiary syphilis had an asymptomatic 70 mm bilobed thoracoabdominal aortic aneurysm with two contiguous saccular components, severe T11 to T12 vertebral body erosion, complete celiac artery occlusion, and critical ostial stenosis of the superior mesenteric and right renal arteries, with mature collateral perfusion from the inferior mesenteric artery. After preoperative penicillin therapy, open repair with selective left renal artery reimplantation and intentional nonreconstruction of the chronically occluded visceral branches was completed without paraplegia or mesenteric ischemia.

Cardiovascular syphilis, once a leading cause of thoracic aortic aneurysm, became uncommon after the introduction of penicillin but has re-emerged: reported cases in Japan more than doubled between 2020 and 2022, with surges also in North America, Europe, and Asia.^1,2 Cardiovascular involvement follows 10 to 30 years after primary infection through obliterative endarteritis of the vasa vasorum and predominantly affects the ascending aorta and arch; only 11.3% of syphilitic aortic aneurysms involve the aorta distal to the arch, and thoracoabdominal involvement is exceptional.3, 4, 5

The authors describe a syphilitic thoracoabdominal aortic aneurysm combining three rarely cooccurring features: a Crawford extent III bilobed saccular aneurysm, severe T11 to T12 vertebral erosion, and chronic occlusion or critical stenosis of three of four visceral branches with mature collateralization. Written publication consent was obtained.

Case report

A 55-year-old man with hypertension and hyperuricemia was referred after screening abdominal ultrasound incidentally identified an aortic aneurysm. He was asymptomatic, with no intravenous drug use, connective tissue disease, or known sexually transmitted infection. Syphilis serology is included in the routine preoperative screening, together with hepatitis and human immunodeficiency virus testing. Independently, the aneurysm morphology had raised suspicion of an infected aneurysm: a bilobed saccular aneurysm with a diffusely thickened adventitia, and minimal atherosclerotic calcification in a relatively young man, features that placed infectious and inflammatory aortitis high in the differential diagnosis. Serology was strongly reactive for rapid plasma reagin (RPR; 171.8 R U; cutoff < 0.9 R U) and for Treponema pallidum (TP) antibody (4929 U/mL; cutoff < 5 U/mL). Human immunodeficiency virus testing was negative, and cerebrospinal fluid and ophthalmologic evaluations were normal, excluding neurosyphilis and ocular syphilis.^{6,7 18}F-fluorodeoxyglucose positron emission tomography was not performed, because the diagnosis was established serologically and would not have altered the operative indication.

Computed tomography angiography (CTA) showed a 70 mm bilobed aneurysm extending from the distal descending thoracic aorta into the upper abdominal aorta, with a dorsally projecting upper sac eroding T11 and T12 and a ventrally projecting lower sac (Fig 1, A-C). The celiac trunk was occluded, the superior mesenteric artery (SMA) and right renal artery (RRA) were critically stenotic at their ostia, and the right kidney was atrophic (Fig 1, D and E). The left renal artery (LRA) and left kidney were normal, and extensive collaterals from an enlarged inferior mesenteric artery (IMA) supplied the foregut and midgut (Fig 1, A). Orthopedic spine surgeons confirmed erosion confined to the anterior vertebral bodies, without posterior element involvement, canal compromise, or instability; no stabilization was advised.

Fig 1.

Preoperative computed tomography. A, Three-dimensional volume-rendered reconstruction showing the bilobed thoracoabdominal aortic aneurysm with two contiguous saccular components (a dorsally projecting upper sac and a ventrally projecting lower sac; red arrows) and an enlarged inferior mesenteric artery with rich collateral pathways supplying the foregut and midgut. Dashed lines indicate the levels of the axial sections in (B) and (D). B and C, Axial and sagittal reformats demonstrating severe pressure erosion of the anterior cortex of T11 and T12 by the dorsal sac (arrowheads). D, Axial reformat showing severe stenosis of the right renal artery (white arrow). E, Sagittal reformat showing complete celiac artery occlusion at the level of the lower sac, with severe ostial stenosis of the superior mesenteric artery (black arrow).

Benzathine penicillin G, 2.4 million units intramuscularly weekly for three doses, was given preoperatively per current guidelines for tertiary syphilis with normal cerebrospinal fluid.⁷ Adequacy was defined by completion of the full three-dose regimen; serologic cure was not expected this early, because nontreponemal titers in late syphilis fall slowly and a transient post-treatment rise is recognized. Titers accordingly rose mildly immediately before operation (RPR, 208.2 R U; TP, 5136 U/mL); repeat CTA after therapy showed no interval change in aneurysm size or morphology.

Open repair was performed through a left thoracoabdominal incision entering the seventh intercostal space, with cerebrospinal fluid drainage, mild hypothermia (34-35 °C), motor-evoked potential monitoring, sequential cross-clamping, and selective cold renal perfusion (Fig 2, A and B).^8,9 The proximal clamp was applied to the descending thoracic aorta at the ninth intercostal space, proximal to the neck of the upper sac, with a second clamp on the mid-descending aorta so that the proximal anastomosis was made in a sequentially clamped field; the distal clamp was then moved to the infrarenal aorta below the LRA. Proximal cross-clamp time was 45 minutes, total aortic cross-clamp time was 146 minutes, and left renal cold perfusion time was 109 minutes. The adventitia was thickened and periaortic adhesions dense, consistent with syphilitic aortitis (Fig 2, B).¹⁰ The diseased segment was replaced with a woven polyester graft, the proximal anastomosis beveled to keep the ostium of the major T10 intercostal artery, considered important from prominent back bleeding, in continuity with the native aortic cuff. The chronically occluded SMA and RRA were intentionally not reconstructed, the distal anastomosis being beveled so that their ostia remained in continuity with the residual native aorta and its collateral inflow. Only the LRA, supplying the sole functioning kidney, was reconstructed via a separate side branch. An omental wrap was not used; however, there was no pyogenic infection, the treponemal aortitis had been treated, and the graft was covered with the residual aneurysm wall.

Fig 2.

Intraoperative findings. A, Overall view of the bilobed thoracoabdominal aortic aneurysm (arrowheads) after thoracotomy. B, Dense periaortic inflammatory adhesions and a thickened, indurated adventitia surrounding the aneurysm (white arrow), consistent with syphilitic aortitis. C, View of the opened aneurysm sac showing the eroded T11 and T12 vertebral bodies, where loss of the intimal layer over the area of direct contact left the cancellous bone directly exposed and bleeding (black arrow).

Within the opened sac the intima was absent over the segment contacting the eroded vertebrae, and active bleeding from exposed cancellous bone of T11 and T12 was observed (Fig 2, C). Hemorrhage was controlled with argon beam coagulation followed by layered oxidized regenerated cellulose, fibrin sealant, and packing (Fig 3, A).11, 12, 13 The patient was extubated on postoperative day 1. Acute kidney injury required hemodialysis for 16 days, after which renal function returned to baseline. There were no paraplegia and no mesenteric ischemia, and the patient was discharged home ambulating independently on postoperative day 25. Histology showed obliterative endarteritis of the vasa vasorum with adventitial lymphoplasmacytic infiltration; cultures and spirochete stains were negative.^14,15 Postoperative CTA confirmed graft and LRA patency (Fig 3, B). Titers had declined markedly at 1 month (RPR, 55.4 R U; TP, 3080 U/mL).

Fig 3.

Intraoperative and postoperative findings. A, Intraoperative photograph after completion of the repair, showing the graft replacing the diseased aortic segment, with a side branch reimplanted to the left renal artery. B, Postoperative three-dimensional computed tomography confirming patent proximal and distal aortic anastomoses, patent left renal artery side branch, and unchanged ostial stenosis of the superior mesenteric artery with preserved distal mesenteric perfusion through rich collateral pathways from an enlarged inferior mesenteric artery.

Discussion

Four issues warrant emphasis. First, syphilitic involvement of the thoracoabdominal aorta is exceptional.3, 4, 5 Unlike a recent open repair of a syphilitic thoracoabdominal aneurysm,¹⁶ the present case combined severe vertebral erosion with chronic multibranch visceral occlusion, a combination not previously described.¹⁷ Given the global resurgence of syphilis,^1,2 more such cases are likely.

Second, thoracic endovascular aortic repair was considered and rejected. The distal end of the aneurysm lay immediately proximal to the visceral segment, so no distal landing zone of adequate length was available and the risk of a type IB endoleak was prohibitive. Extending the seal caudally was not an option either; the celiac artery was occluded, and the SMA and RRA were critically stenotic, so a fenestrated-branched device had no cannulable targets, and coverage of the visceral aorta would have threatened the IMA collaterals supplying the foregut, midgut, and right kidney. Custom-made devices are not available at our institution; furthermore, the eroded segment with an absent intimal layer indicated transmural wall destruction rather than a sealable neck. In a 55-year-old man, open graft replacement offered the more durable repair and was therefore preferred.

Third, the chronic visceral occlusive disease reframed the surgical strategy. Crawford extent III repair conventionally requires reimplantation of the celiac, SMA, and renal arteries^8,9; here, mature IMA-based collaterals already perfused the foregut, midgut, and right kidney, and dense adhesions around the stenotic ostia precluded safe dissection. Selective nonreconstruction with revascularization of the sole functioning kidney avoided mesenteric ischemia and caused only transient renal failure, but should not be generalized to patients with patent or noncollateralized visceral arteries.

Fourth, vertebral erosion produces brisk cancellous bleeding when the sac is opened.11, 12, 13 It is rarely reported in syphilitic aneurysm, usually in the descending thoracic aorta and often with myelopathy^18,19; Heggtveit³ found it in two of 100 syphilitic aortitis cases. Here, the eroded segment caused no neurologic compromise, and preservation of T10 intercostal flow, cerebrospinal fluid drainage, mild hypothermia, motor-evoked potential monitoring, and sequential clamping were associated with no spinal cord injury.

Limitations include the single patient experience and the dependence of this strategy on pre-existing collateral anatomy.

Conclusions

Open repair of a syphilitic thoracoabdominal aortic aneurysm with vertebral erosion and chronic multibranch visceral occlusion was completed without paraplegia or mesenteric ischemia. Selective nonreconstruction of well-collateralized branches, revascularization of the sole functioning kidney, organ-protection adjuncts, and meticulous control of vertebral bleeding were central. As syphilis re-emerges, a low threshold for treponemal serology in unexplained saccular or inflammatory aortic aneurysms is warranted.

Funding

None.

Declaration of generative AI and AI-assisted technologies in the manuscript preparation process

During the preparation of this work, the authors used Claude (Anthropic) to assist with spell-checking and grammatical refinement of the English manuscript. After using this tool, the authors reviewed and edited the content as needed and take full responsibility for the content of the publication.

Patient consent

Written informed consent for publication of clinical details and deidentified images was obtained from the patient. The signed consent form is retained by the corresponding author and will be made available to the editorial office on request.

Reporting guideline

This case report is reported in accordance with the CARE (CAse REport) guideline.

Disclosures

The authors declare that they have no conflicts of interest.