Abstract

Retroperitoneal paragangliomas are neuroendocrine tumors originating from chromaffin cells in the sympathetic nerves. These tumors are commonly located around the abdominal aorta and inferior vena cava and can cause significant bleeding during surgery due to their hypervascular nature. In such cases, preoperative selective embolization can facilitate tumor resection and reduce both morbidity and mortality. This case report presented a 38-year-old male patient with a retroperitoneal paraganglioma who underwent surgery following preoperative embolization due to tumor hypervascularity.

Paragangliomas (PGLs) are neuroendocrine tumors originating from extra-adrenal chromaffin cells.[1, 2] They are divided into two types based on their clinical and biological characteristics: sympathetic and parasympathetic.[3] Sympathetic PGLs account for 80% of cases, while parasympathetic PGLs account for 20%.[3, 4] While most PGLs are benign, approximately 10% can have a malignant course.[5] This case report presented a patient with a retroperitoneal PGL who underwent surgery following preoperative embolization.

Case Presentation

A 38-year-old male presented with complaints of persistent right upper quadrant pain over one month. Contrast-enhanced computed tomography (CT) revealed a paraaortic solid mass ( Figure s 1a, b). The images showed an intensely enhancing mass (measuring 87?68 mm) adherent to the right ureter. Preoperative laboratory tests showed that the tumor was hormone-negative. Given the hypervascularity of the tumor observed on the CT images and the increased risk of bleeding during the planned surgical resection, the interventional radiology department recommended preoperative coil and particle embolization. The patient was transferred to the interventional radiology department. Under local anesthesia, a 5F introducer was placed in the right common femoral artery. Abdominal aortic angiography was performed by injecting contrast medium with a 5F pigtail catheter to determine the possible feeding arteries of the mass. Afterward, selective catheterization was performed with a 4F Simmons 1 catheter (Boston Scientific, Massachusetts, USA) for the confirmed feeding arteries. After selective catheterization of the feeding arteries, a 2.4F microcatheter (Progreat; Terumo Medical Corp, Tokyo, Japan) and microguidewire were placed in a location close to the mass. Embolization was performed using 2- and 3-mm coils (Concerto; Ev3, Plymouth, Minnesota, USA) and 355- to 500-?m PVA particle embolizing agents (PVA-Contour; Boston Scientific, Natick, MA, USA) to the arterial feeders of the mass ( Figure s 2a-c). A final angiography was performed after embolization. There was no contrast enhancement left in the feeding arteries of the mass. Written informed consent was obtained from the patient.

Figure 1: (a, b) Contrast-enhanced computed tomography revealed that the tumor was located immediately behind the inferior vena cava and the right side of the abdominal aorta.

Figure 2: (a, b) Angiogram showing the hypervascular nature of the tumor before embolization. (c) Angiogram after the embolization of the artery that was supplying the tumor.

Since the mass was adherent to the right ureter, a preoperative double-J stent catheter was inserted by surgeons in the urology department following the embolization. Surgery was performed with direct arterial monitoring to manage hemodynamic instability during the resection. A laparotomy was performed through an abdominal incision, enabling access to the retroperitoneum. During exploration, a solid and highly vascular mass was detected beneath the right kidney, attached to the inferior vena cava ( Figure 3a). Using blunt dissection, the mass was carefully separated from the vascular structures and resected in one piece ( Figure 3b). There were no hemodynamic issues or significant bleeding during the surgery. Pathological examination of the resected mass confirmed the PGL diagnosis. The patient"s double-J stent catheter was removed on the fifth postoperative day. The patient experienced no issues during the hospital stay and was discharged on the sixth postoperative day without complications.

Figure 3: (a) Intraoperative image after exploration of the paraaortic solid mass. (b) An image of the completely resected tumor.

Discussion

Retroperitoneal PGLs are frequently located near the abdominal aorta and inferior vena cava.[2] Around 80 to 90% of retroperitoneal PGLs originate from the adrenal glands, while 10 to 20% are of extra-adrenal origin.[5] Unlike their adrenal counterparts, extra-adrenal PGLs do not usually cause symptoms due to hormone or catecholamine release.[5] Consequently, nonfunctional PGL diagnoses are usually incidental. Conversely, functional PGLs are typically identified during tests for hypertension. Paraganglioma can be diagnosed using CT, magnetic resonance imaging, scintigraphy, and positron emission tomography.[2] Contrast-enhanced CT is the first choice due to its effective display of the blood supply to the tumor.[2] Magnetic resonance imaging is preferred in patients in whom CT cannot be performed. Positron emission tomography and scintigraphy are important for evaluating metastases. Differential diagnoses that should be considered for PGLs are liposarcomas, retroperitoneal sarcomas, neurofibromas, pancreatic tumors, leiomyosarcoma, lymphomas, and metastatic masses.[2]

The standard PGL treatment is surgical resection, although successful resections using laparoscopic surgery have also been reported.[3, 6] While the transperitoneal approach is preferred in some series of laparoscopic surgery, the retroperitoneal approach is favored in others.[3, 6] Hakariya et al.[6] recommended the transperitoneal approach because it provides a wide field of view, can be easily converted to open surgery, and allows for easier identification of anatomical relationships. In cases of planned laparoscopic intervention, it is crucial to carefully evaluate the location of the tumor, its adhesion to surrounding tissue, and its vascularity in the preoperative phase. For inoperable cases with metastasis, chemotherapy (e.g., cyclophosphamide, vincristine, and dacarbazine) and radiotherapy should be considered.[5] In cases of planned surgical resection, preoperative detection of tumor vascularization through imaging methods will aid the surgeon during surgery and reduce the risk of significant bleeding. Preoperative embolization is recommended for these patients to facilitate surgical resection.[1, 4] The literature indicates that preoperative embolization not only reduces bleeding during surgical resection but also helps prevent possible catecholamine discharge in functional tumors.[2, 4] Houari et al.[4] performed surgical resection three days after preoperative arterial embolization in a case of hormone-active retroperitoneal PGL. Similarly, Rosing et al.[2] performed a resection by preoperative embolization in retroperitoneal PGL cases. Doğusoy et al.[1] encountered excessive bleeding during their first attempt at resecting a mediastinal PGL via thoracotomy. However, after performing selective embolization, they successfully removed the mass in a second session one week later.

In conclusion, PGLs are rare tumors that often present without specific symptoms. When surgical resection is planned, due consideration must be given to the blood supply of the tumor. Tumors with high vascularity can cause significant intraoperative bleeding, making preoperative selective embolization essential. This approach not only facilitates tumor resection but also helps reduce surgery-related morbidity and mortality.

Data Sharing Statement: The data that support the findings of this study are available from the corresponding author upon reasonable request.

Author Contributions: Concept, literature review, writing, references and fundings: H.R.; Design: H.R., V.Ç.; Supervision, data collection and/or processing, analysis and/or interpretation, critical review, materials: V.Ç.

Conflict of Interest: The authors declared no conflicts of interest with respect to the authorship and/or publication of this article.

Funding: The authors received no financial support for the research and/or authorship of this article.

References

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2) Rosing JH, Jeffrey RB, Longacre TA, Greco RS. Massive extra-adrenal retroperitoneal paraganglioma: Pre-operative embolization and resection. Dig Dis Sci 2009;54:1621-4. doi:101007/s10620-009-0804-6.

3) Yang Y, Wang G, Lu H, Liu Y, Ning S, Luo F. Haemorrhagic retroperitoneal paraganglioma initially manifesting as acute abdomen: A rare case report and literature review. BMC Surg 2020;20:304. doi: 10.1186/s12893-020-00953-y.

4) Houari N, Touzani S, Salhi H, Alaoui Lamrani MY, Ibnmajdoub K, El Ouahabi H, et al. Retroperitoneal paraganglioma-induced cardiogenic shock rescued by preoperative arterial embolization. Case Rep Crit Care 2018;2018:4058046. doi: 10.1155/2018/4058046.

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6) Hakariya T, Shida Y, Ito H, Ueda Y, Kurata H, Ohtsubo A, et al. Successful laparoscopic resection of a paraganglioma immediately behind the inferior vena cava and bilateral renal veins. IJU Case Rep 2019;2:261-4. doi: 10.1002/iju5.12097.