Laparoscopic retroperitoneal paraganglioma resection: a case description

Introduction

Paraganglioma (PGL) is a rare neuroendocrine tumor originating from neural crest cells, with an estimated incidence of 0.005–0.1%, accounting for 1–3% of all retroperitoneal tumors (1,2). Tumors arising from the adrenal medulla are termed pheochromocytomas, while those occurring at extra-adrenal sites are designated as PGLs, also known as ectopic pheochromocytomas. Retroperitoneal PGLs typically have an insidious onset, are difficult to detect in the early stages, and present with diverse clinical manifestations. They may be functional (catecholamine-secreting) or non-functional, further increasing the complexity of clinical diagnosis and surgical management. In this article, we report a case of retroperitoneal PGL with emphasis on its imaging features and surgical management.

Case presentation

All the procedures in this study were performed in accordance with the Declaration of Helsinki and its subsequent amendments. This study was approved by the Ethics Committee of Tongxiang First People’s Hospital. Written informed consent was obtained from the patient for the publication of this article and the accompanying images. A copy of the written consent form is available for review by the editorial office of this journal.

A 67-year-old female patient was admitted to Tongxiang First People’s Hospital with a chief complaint of “a self-detected mass in the right upper abdomen without associated pain for two days.” She denied fever, nausea, vomiting, abdominal pain, diarrhea, headache, palpitations, or diaphoresis. She had a medical history of Parkinson’s disease for over 2 years, with no history of hypertension. She was not on any medication for Parkinson’s disease at the time of admission or during the preoperative evaluation; therefore, drug interference with urinary metanephrine (MN) and vanillylmandelic acid (VMA) measurements was considered unlikely.

The patient was 153 cm in height and weighed 61 kg. Physical examination revealed no palpable superficial lymphadenopathy. The abdomen was flat, with no visible intestinal patterns or peristaltic waves. Bowel sounds were 4 times per minute. The abdomen was soft, with no tenderness or rebound tenderness. A mass measuring approximately 75 mm in greatest diameter was palpable in the right upper abdomen; the mass was firm, with indistinct borders, no tenderness, and moderate mobility.

Admission laboratory findings were unremarkable: white blood cell count, 5.3×10⁹/L; red blood cell count, 4.10×10¹²/L; hemoglobin, 124 g/L; and platelet count, 243.0×10⁹/L. The fecal occult blood test was negative. Tumor markers, including carcinoembryonic antigen (CEA), alpha-fetoprotein (AFP), and carbohydrate antigen 19-9 (CA19-9), were within normal limits. Plasma and urinary MN, normetanephrine (NMN), and urinary VMA were also within normal ranges.

Contrast-enhanced abdominal computed tomography (CT) performed during the preoperative evaluation revealed a lobulated soft tissue mass with heterogeneous density in the right upper abdomen, measuring approximately 75 mm × 60 mm. The solid components of the lesion showed marked heterogeneous enhancement in the arterial phase, with tortuous feeding vessels visible within the lesion. Enhancement decreased slightly during the portal venous and delayed phases, demonstrating early marked enhancement with sustained contrast retention. Non-enhancing cystic components were also observed within the lesion (Figure 1). The tumor was located in the right upper retroperitoneum, anterior to the descending duodenum. It was clearly separated from the right adrenal gland and kidney, with no involvement of the inferior vena cava or abdominal aorta. This location corresponds to a relatively common site for retroperitoneal PGL, which frequently arises in the para-aortic region.

Figure 1 Abdominal CT findings. (A,B) Abdominal CT showing a lobulated soft tissue mass with heterogeneous density in the right upper abdomen. (C,D) Contrast-enhanced CT in the arterial phase demonstrating marked heterogeneous enhancement of the solid components, with tortuous feeding vessels (black arrow) and non-enhancing cystic areas (white arrow). CT, computed tomography.

Contrast-enhanced upper abdominal magnetic resonance imaging (MRI) revealed a mass with heterogeneous signal intensity in the right upper abdomen, measuring approximately 75 mm × 60 mm. The lesion demonstrated low signal intensity on T1-weighted imaging (T1WI) and high signal intensity on T2-weighted imaging (T2WI). On diffusion-weighted imaging (DWI), the lesion showed hyperintensity with corresponding hypointensity on the apparent diffusion coefficient (ADC) map, indicating restricted diffusion. Delayed heterogeneous enhancement was observed, with areas of non-enhancement within the lesion (Figure 2).

Figure 2 Upper abdominal MRI findings. (A,B) The mass showed hypointense signal on T1WI and hyperintense signal on T2WI. (C,D) DWI demonstrated hyperintensity (C), with corresponding hypointensity on the ADC map (D), indicating restricted diffusion. ADC, apparent diffusion coefficient; DWI, diffusion-weighted imaging; MRI, magnetic resonance imaging; T1WI, T1-weighted imaging; T2WI, T2-weighted imaging.

Following preoperative preparation, including blood pressure monitoring and fluid resuscitation, alpha-blockade was not administered, as normal plasma and urinary MN levels indicated a non-functional tumor. The patient underwent transperitoneal laparoscopic retroperitoneal tumor resection under general anesthesia nine days after admission. Intraoperatively, a solitary retroperitoneal mass measuring approximately 75 mm × 60 mm was identified, with a firm consistency (Figure 3). The tumor was dissected from the periphery inward, revealing abundant vascularity with numerous tortuous vessels on the surface and an intact capsule. Complete tumor resection was achieved. Intraoperatively, the patient’s blood pressure remained stable (110–130/65–80 mmHg) without significant fluctuations during tumor manipulation. No vasopressor support was required postoperatively. The resected specimen measured 75 mm × 60 mm × 50 mm. The cut surface was cystic-solid, with gray-yellow material within the cystic component and gray-red solid areas with hemorrhage; the capsule was intact (Figure 4).

Figure 3 Intraoperative laparoscopic view. A solitary retroperitoneal mass with firm consistency, measuring approximately 75 mm × 60 mm, with abundant tortuous vessels on the surface.

Figure 4 Tumor specimen. (A-C) The tumor measured approximately 75 mm × 60 mm × 50 mm, with an intact capsule. (D) The cut surface was cystic-solid, containing gray-yellow material within the cystic component and gray-red solid areas with hemorrhage.

Postoperative pathology obtained three days after surgery revealed PGL, characterized by tumor cells arranged in an organoid pattern with abundant cytoplasm and rich vascular stroma. Immunohistochemistry showed positive staining for chromogranin A (CgA), synaptophysin (Syn), CD56 (neural cell adhesion molecule), and S-100 (S-100 protein), with a Ki-67 (proliferation marker protein) proliferation index of 1% (Figure 5). The patient was discharged on postoperative day 8 without complications such as intra-abdominal hemorrhage, intestinal obstruction, or wound infection. At one year follow-up post-surgery, no evidence of tumor recurrence or metastasis was observed.

Figure 5 Postoperative pathology and immunohistochemical results. (A) Histopathological examination confirmed a diagnosis of paraganglioma (hematoxylin-eosin, ×50). (B-E) Immunohistochemistry showed positive staining for CgA (B), Syn (C), CD56 (D), and S-100 (E) (×50). CD56, neural cell adhesion molecule; CgA, chromogranin A; S-100, S-100 protein; Syn, synaptophysin.

Discussion

PGL can occur at any age. Most PGLs are benign but have malignant potential and may metastasize. Based on biological behavior, PGL can be classified into two types: sympathetic and parasympathetic. Sympathetic PGLs are predominantly distributed along the abdominal sympathetic trunk and often secrete catecholamines, while parasympathetic PGLs are mostly located in the head and neck region and are typically non-functional. PGLs can arise in various locations throughout the body, with the retroperitoneum being the most common site. They frequently occur in the organ of Zuckerkandl, located between the origin of the inferior mesenteric artery and the bifurcation of the abdominal aorta, followed by the perirenal region and sacrococcygeal area. Rarely, they may occur in the liver, gallbladder, or pancreas (3).

PGLs can be classified as functional or non-functional based on whether they secrete excessive catecholamines and produce corresponding clinical symptoms. The classic clinical manifestation of functional tumors include paroxysmal hypertension and the “Menard triad” (headache, palpitations, and diaphoresis); however, only about 25% of patients present with the complete triad (4). Functional tumors can induce severe cardiovascular events due to excessive catecholamine release, resulting in high mortality rates. Non-functional tumors account for approximately 24–75% of cases (5). Because patients with non-functional tumors often lack typical symptoms, the tumors are frequently discovered incidentally on imaging studies, hence the term “incidentalomas” (5). Clinical diagnosis is challenging, as most patients present with atypical symptoms. It should be noted that methoxytyramine (3-MT) was not measured in this case; thus, so a dopamine-secreting PGL could not be completely excluded. Thus, “non-functional” in this report refers to the absence of clinical symptoms and normal standard biochemical testing (MN, NMN, and VMA).

Imaging examination is an essential adjunctive tool for diagnosing retroperitoneal PGL. Contrast-enhanced CT and MRI are the preferred imaging modalities: CT clearly delineates tumor location, size, and relationship with adjacent vascular structures, while MRI offers superior soft tissue resolution, providing advantages in detecting extra-adrenal lesions.

Typical imaging features of retroperitoneal PGL include: a predilection for the organ of Zuckerkandl region; predominantly heterogeneous solid or cystic-solid oval or lobulated masses with well-defined borders; and marked hypervascularity with abundant intratumoral capillary networks, characterized by early marked enhancement with sustained contrast retention on enhanced imaging (6). Tortuous and thickened vessels are often visible around the tumor or within solid components (7). Cystic degeneration and necrosis are common (particularly in larger tumors), while calcification is rare. On MRI, lesions typically show hypointensity on T1WI and hyperintensity on T2WI, with heterogeneous enhancement of solid components and non-enhancing necrotic areas.

For retroperitoneal masses with significant cystic degeneration and necrosis on imaging, PGL should be considered in the differential diagnosis. In addition to conventional imaging, ¹³¹I-metaiodobenzylguanidine (MIBG) or ¹²³I-MIBG scintigraphy serves as an important adjunct for functional localization. In the present case, MIBG scintigraphy was not performed, as the tumor was biochemically non-functional (normal MN, NMN, and VMA levels), and the diagnosis was clearly established by CT and MRI findings, which were considered sufficient for surgical planning.

Imaging not only facilitates tumor characterization and differential diagnosis but also provides crucial information for surgical planning. Although the patient was asymptomatic, the MRI findings, including T2WI hyperintensity, heterogeneous enhancement, and cystic degeneration, were consistent with typical PGL imaging features, suggesting that imaging can provide critical diagnostic clues for PGL regardless of functional status; however, imaging alone cannot differentiate between functional and non-functional tumors, which requires biochemical testing.

In this case, despite normal catecholamine laboratory tests, PGL was strongly suspected preoperatively based on characteristic imaging findings, including: (I) early marked heterogeneous arterial enhancement with tortuous feeding vessels; (II) sustained contrast retention; (III) T2WI hyperintensity with cystic degeneration; and (IV) restricted diffusion on DWI/ADC. Collectively, these features favored PGL over gastrointestinal stromal tumor (GIST) (which typically shows less intense enhancement) and liposarcoma (which typically contains fat components). Consequently, laparoscopic resection was performed for both diagnostic confirmation and therapeutic purposes, with appropriate perioperative precautions, including blood pressure monitoring and fluid resuscitation.

Measurement of hormones and their metabolites is also crucial for the qualitative diagnosis of PGL. Plasma and urinary MN and NMN are the preferred laboratory tests, as they significantly enhance diagnostic sensitivity for pheochromocytoma and PGL while reducing false-negative rates (8). Additionally, VMA measurement provides complementary diagnostic information (9).

Retroperitoneal PGL should be differentiated from the following conditions: (I) GIST, which commonly occurs in individuals aged 50–60 years, is prone to necrosis and cystic degeneration in tumors >50 mm, demonstrates moderate to marked enhancement that is generally less intense than that of PGL, typically shows delayed enhancement, and rarely presents with tumor vessels; (II) liposarcoma, which exhibits diverse imaging findings with high tumor heterogeneity, typically demonstrates heterogeneous progressive enhancement, shows gradual enlargement, and may be associated lymphadenopathy or ascites (whereas PGL rarely contains fat components); and (III) Castleman disease, which can occur in any lymph node region but most commonly involves the mediastinum, has the hyaline vascular type as the most frequent subtype, demonstrates marked enhancement due to abundant capillaries, similar to adjacent large vessels, and exhibits characteristic dendritic calcification, which serves as an important distinguishing feature.

In the present case, tumor markers (CEA, AFP, and CA19-9) were within normal limits, and imaging revealed no fat components or dendritic calcification; therefore, liposarcoma and Castleman disease were initially excluded clinically, and the diagnosis of PGL was ultimately confirmed by immunohistochemical pathology. However, the imaging findings—including early marked heterogeneous enhancement in the arterial phase with tortuous feeding vessels, sustained contrast retention, and T2WI hyperintensity—strongly supported a preoperative diagnosis of PGL over other retroperitoneal tumors.

Surgery remains the primary and most important treatment modality for PGL. Given that this tumor is insensitive to radiotherapy and chemotherapy, radical complete resection should be performed as early as possible after diagnosis. Adequate perioperative management is crucial for surgical success. For patients with functional or subclinical tumors, thorough preoperative pharmacological preparation (e.g., alpha-blockade for blood pressure control and appropriate volume expansion) is essential to reduce the risk of hypertensive crisis, arrhythmias, and stroke caused by massive catecholamine release due to tumor manipulation or compression during surgery, while also preventing persistent hypotension or shock following the sharp decline in catecholamines after tumor resection. Intraoperative manipulation should be gentle and meticulous, avoiding tumor compression, and maintaining capsular integrity whenever possible. This is essential for reducing intraoperative blood pressure fluctuations and ensuring surgical safety.

With advances in minimally invasive techniques, laparoscopic surgery (including robotic surgery) is increasingly being applied for PGL resection. Compared with conventional open surgery, it offers advantages such as reduced trauma, decreased postoperative pain, faster recovery, shorter hospital stays, and lower complication rates, all of which have been widely demonstrated in clinical practice (10). In the present case, a transperitoneal approach was selected because the tumor was located in the right upper retroperitoneum anterior to the descending duodenum, facilitating access and vascular control.

Definitive diagnosis of retroperitoneal PGL relies on postoperative pathology and immunohistochemistry. Gross specimens typically appear nodular, with a large volume, well-defined borders, and an intact capsule. The cut surface is solid or cystic-solid, gray-white or gray-red, soft in consistency, and often accompanied by hemorrhage, necrosis, and cystic changes.

Microscopically, the tumor consists of chief cells and sustentacular cells. Chief cells are numerous, round or polygonal, with abundant eosinophilic granular cytoplasm, arranged in organoid, nested, diffuse, or acinar patterns, and may exhibit atypia and mitotic activity. Sustentacular cells are spindle-shaped, arranged in a single layer surrounding the chief cells. The tumor stroma consists of fibrovascular tissue with abundant sinusoids.

Immunohistochemically, characteristic expression patterns are observed: chief cells are positive for neuroendocrine markers such as CgA, Syn, CD56, and neuron-specific enolase (NSE), and are negative for the epithelial marker cytokeratin (CK); while sustentacular cells express S-100 protein. Additionally, vimentin (Vim) and Ki-67 are frequently positive.

PGL has a certain malignant potential; therefore, patients require lifelong follow-up to monitor for recurrence or metastasis. Germline genetic testing for SDHx, VHL, RET, and NF1 mutations was not performed in this patient due to the absence of a family history and a lack of clinical suspicion for hereditary syndromes; however, it is recommended for patients with multifocal, recurrent, or metastatic disease or a positive family history.

Conclusions

This case highlights the diagnostic value of imaging in suggesting a diagnosis of retroperitoneal PGL prior to biochemical confirmation and pathological examination, and demonstrates that laparoscopic resection with adequate perioperative management is safe and effective. Lifelong follow-up is essential given the malignant potential of this tumor.

Acknowledgments

None.

Footnote

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://qims.amegroups.com/article/view/10.21037/qims-2026-0752/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the Declaration of Helsinki and its subsequent amendments. This study was approved by the Ethics Committee of Tongxiang First People’s Hospital. Written informed consent was obtained from the patient for publication of this article and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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