Functional Retroperitoneal Paraganglioma of the Organ of Zuckerkandl: A Multimodality Imaging Case Study

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 Functional Retroperitoneal Paraganglioma of the Organ of Zuckerkandl: A Multimodality Imaging Case Study

주커칸들 기관의 기능성 후복막 부신경종: 다중 모달리티 영상 사례 연구

Introduction

Retroperitoneal paragangliomas are rare, highly vascular neuroendocrine tumors arising from extra-adrenal chromaffin cells. Among them, the paraganglioma of the organ of Zuckerkandl—a small aggregation of chromaffin tissue located near the origin of the inferior mesenteric artery (IMA)—represents a diagnostically challenging and clinically significant entity. This case study presents a 30-something-year-old male with hypertension and abdominal pain, highlighting the integration of CT, MRI, and DOTATATE PET/CT imaging to reach the diagnosis.

Keywords: retroperitoneal paraganglioma, organ of Zuckerkandl, hypertension, functional tumor, DOTATATE PET/CT, somatostatin receptor, catecholamine, T2 hyperintensity

Case Presentation

A man in his 30s presented with sustained hypertension and intermittent abdominal pain. He had no significant past medical history, and a laboratory workup revealed elevated serum catecholamines. Initial non-contrast CT imaging of the abdomen and pelvis was performed, followed by contrast-enhanced MRI, and DOTATATE PET/CT for metabolic characterization.

Imaging Findings

Figure 1. CT Imaging (non-contrast)

A soft tissue mass in the aortocaval space, appearing isodense to adjacent musculature.

The CT scan revealed a lobulated soft tissue mass in the aortocaval region, adjacent to the origin of the IMA. No calcification or central necrosis was identified.

Figure 2. MRI Axial T2 & T1 In-phase/Out-of-phase

Avidly enhancing mass on T2-weighted imaging with a signal drop in out-of-phase sequence suggestive of fat or intracellular lipid.

MRI revealed a T2 hyperintense mass with avid post-contrast enhancement, characteristic of hypervascular tumors. On the out-of-phase sequence, there was a significant drop in signal intensity, indicating intracellular lipid or hemorrhagic components.

Figure 3. DOTATATE PET/CT Scan

Intense DOTATATE uptake in retroperitoneal mass indicating somatostatin receptor overexpression.

The DOTATATE PET/CT demonstrated somatostatin receptor-positive uptake, confirming the neuroendocrine nature of the lesion.

Differential Diagnosis

  • Paraganglioma of the organ of Zuckerkandl ✅

  • Schwannoma

  • Neurofibroma

  • Lymphoma

  • Leiomyosarcoma

The paraganglioma was favored due to clinical symptoms, catecholamine elevation, and somatostatin receptor uptake.

Definitive Diagnosis

The patient underwent surgical resection of the mass. Histopathological examination confirmed paraganglioma. Serum catecholamine levels normalized postoperatively.

Pathophysiology of Paraganglioma of the Organ of Zuckerkandl

Paragangliomas are neuroendocrine tumors derived from extra-adrenal chromaffin cells. The organ of Zuckerkandl, located near the aortic bifurcation or origin of the IMA, is a common site for extra-adrenal paragangliomas. These tumors are often functional, secreting catecholamines, particularly norepinephrine.

Epidemiology

  • Extra-adrenal paragangliomas constitute ~10% of all pheochromocytomas.

  • Incidence: ~2–8 per million/year

  • Typically occurs in the 4th to 5th decade, with no strong gender preference.

Clinical Features

Symptoms result from catecholamine hypersecretion, including:

  • Sustained or paroxysmal hypertension

  • Headache

  • Palpitations

  • Sweating

Biochemical tests show elevated serum and urinary catecholamines/metanephrines.

Imaging Characteristics

ModalityFindings
CTLobulated soft tissue mass, isodense, avid contrast enhancement
MRIT2 hyperintense, T1 isointense to the liver, with intense gadolinium enhancement
DOTATATE PET/CTStrong uptake due to somatostatin receptor expression

Treatment

Surgical resection is the treatment of choice. Preoperative preparation includes:

  • Initiation of alpha-adrenergic blockade

  • Beta-blockade initiated after alpha-blockade (≥7 days later)

Failure to properly manage catecholamine surge may lead to an intraoperative hypertensive crisis.

Prognosis

  • Surgical outcomes are excellent if diagnosed early.

  • Malignancy is rare but possible (~10%).

  • Regular follow-up with imaging and catecholamine levels is essential due to potential recurrence.

Quiz

1. Where is the most significant lesion located?
(1) Bone (2) Colon (3) Liver (4) Retroperitoneum

2. The dominant lesion shows enhancement.
(1) True (2) False

3. The signal in the lesion decreases significantly in out-of-phase images.
(1) True (2) False

4. What does the DOTATATE tracer help visualize?
(1) Somatostatin receptor (2) Presynaptic dopamine transporter (3) Glucose metabolism

Answer & Explanation

1. Answer: (4) Retroperitoneum, Explanation: The lesion is clearly located in the aortocaval space, which lies within the retroperitoneum.

2.  Answer: (1) True, Explanation: Post-contrast MRI images show marked enhancement, indicative of a vascular tumor.

3. Answer: (1) True, Explanation: This drop suggests microscopic fat or hemorrhagic material within the lesion.

4. Answer: (1) Somatostatin receptor. Explanation: DOTATATE binds to somatostatin receptors, allowing visualization of neuroendocrine tumors.

Conclusion

This case highlights the crucial role of multimodality imaging—CT, MRI, and DOTATATE PET/CT—in diagnosing a retroperitoneal functional paraganglioma of the organ of Zuckerkandl. Early recognition and surgical resection, combined with proper preoperative management, lead to excellent outcomes. The integration of anatomical and functional imaging is vital for guiding therapy in neuroendocrine tumors.

References

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  3. S. F. Goldstein, et al., “Molecular Imaging in Neuroendocrine Tumors,” Clin Nucl Med, vol. 45, no. 6, pp. 439–446, 2020.

  4. P. T. Pacak, “Preoperative Management of Pheochromocytoma,” JAMA, vol. 295, no. 21, pp. 2431–2436, 2006.

  5. M. G. Eisenhofer, et al., “Biochemical diagnosis of pheochromocytoma,” Endocr Relat Cancer, vol. 15, pp. 157–164, 2008.

  6. J. M. Taïeb and J. F. Fassnacht, “Paraganglioma: diagnostic and therapeutic update,” Lancet Diabetes Endocrinol, vol. 7, no. 4, pp. 301–313, 2019.

  7. M. W. Saeed, et al., “Organ of Zuckerkandl Paraganglioma: Multimodality Imaging,” J Clin Imaging Sci, vol. 10, p. 12, 2020.

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