Mesenteric Paraganglioma: A Case Report and Literature Review

We report a rare case of a solitary paraganglioma arising from the small bowel mesentery, found in a 70-year-old female who presented with abdominal pain. Paragangliomas are rare neuroendocrine, neural crest-derived tumors, most commonly found in the adrenal medulla. While extra-adrenal paragangliomas arise from diverse locations, mesenteric origins are extremely rare. Our comprehensive review shows 35 previously documented cases and updates the epidemiology, clinical features, and outcomes of mesenteric paragangliomas.


Introduction
Paragangliomas (PGLs) are rare neuroendocrine neoplasms of neural crest origin that arise from autonomic paraganglia.There are two main types of extra-adrenal paragangliomas: head and neck, and abdominal.The head and neck PGLs are more common and often occur around the carotid artery, jugular vein, and along the base of the skull.Extra-adrenal abdominal PGLs can develop in various locations within the abdomen, including the abdomen's sympathetic and parasympathetic nerve chains.
The incidence of PGLs overall is 1-2/100,000 [1].However, extra-adrenal PGLs found in the mesentery are exceedingly rare, with one study reporting only 12 documented cases [2].We report a rare case of extraadrenal paraganglioma presenting as a mesenteric mass.In addition, we present a comprehensive review of documented cases to update the epidemiology, clinical features, and outcomes of mesenteric paragangliomas.

Case Presentation
A 70-year-old female patient with a past medical history of sarcoidosis and known mesenteric mass presented with increasing abdominal pain, nausea, diarrhea, and emesis.The mass was first noted six years earlier, however, the patient remained asymptomatic and was monitored regularly with imaging.She had no history of colon cancer and her most recent colonoscopy revealed polyps.
Computed Tomography (CT) of the abdomen pelvis with intravenous (IV) contrast revealed a right paramidline enhancing mass measuring 2.7 x 2.8 x 3.1 cm in the pelvis.The mass appeared mobile as it was in a different position on prior CTs (Figure 1).Magnetic resonance imaging (MRI) showed a T2 hypointense, T1 isointense mesenteric mass measuring 2.4 x 2.9 x 3.0 cm associated with small bowel loops (Figures 2A-2C).

Discussion
We describe a case of small-bowel mesenteric paraganglioma causing abdominal discomfort.We also perform a comprehensive review of the literature using the MEDLINE database as indexed by PubMed with the following search string: "mesenteric" AND "paraganglioma."A total of 60 articles were screened by title and abstract.Twenty-five articles were subsequently excluded if they were cases of paragangliomas in other regions or of different tumors.A comprehensive list of the 35 included cases of mesenteric paragangliomas is summarized in Table 1.
Our review found 36 documented cases of mesenteric paraganglioma, including our current case.Mesenteric paragangliomas occur most commonly in older adults with an average age of 57 years, with a predominance in females (75%).The most common presenting symptom was a palpable abdominal mass (12/36 cases, 33%), but many patients presented with abdominal pain/discomfort (10/36 cases, 28%) or were asymptomatic (10/36 cases, 28%).
The majority of these tumors are benign, but they can still cause significant health issues depending on their size and location.Sympathetic-associated PGLs can often produce hormones such as catecholamines (e.g., adrenaline and noradrenaline), which can lead to symptoms such as high blood pressure, rapid heart rate, and other signs of excessive sympathetic nervous system activity.Malignant PGLs are less common but are often indistinguishable by imaging.Of the cases that reported metastases in our review, 5/28 (18%) found evidence of PGL in nearby lymph nodes.
While a majority of extra-adrenal PGLs are nonfunctional and discovered incidentally during imaging evaluations for other reasons.CT features include a nonspecific soft-tissue density similar to other neoplasms.Therefore, preoperative diagnosis of extra-adrenal PGLs is usually difficult [3].MRI characteristics for PGLs are typically low signal intensity on T1-weighted images and strong enhancement after administration of contrast material.While our case showed a hypo-intense lesion, they are typically hyper-intense on T2-weighted images [4].
While only 25% of PGLs are functional and have the potential to secrete catecholamines, 131 I metaiodobenzylguanidine (MIBG) scintigraphy is a specific imaging study for preoperative diagnosis [5].Furthermore, modern imaging with 68Ga-DOTATATE PET/CT is an accurate technique to diagnose neuroendocrine as it has a reported sensitivity of 83-97% and specificity of 80-100% [6].
The primary treatment choice for PGLs is surgical resection.There have been no reported cases of tumor recurrence, but median follow-up was relatively short.While chemotherapy and radiotherapy may be used for unresectable or metastatic cases, there is no current evidence of increased survival with these treatments [7].

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Conclusions
We report an extremely rare case of a solitary paraganglioma arising from the small bowel mesentery, found in a 70-year-old female who presented with abdominal pain.A comprehensive literature review found only 36 reported cases of mesenteric paragangliomas, including the current case.Although rare, these tumors should be among the preoperative differential diagnosis of abdominal masses of unknown etiology.

FIGURE 4 :
FIGURE 4: Immunohistochemical study results (A) High-power hematoxylin-eosin preparation at 200X magnification demonstrates a highly vascular tumor consisting of epithelioid cells arranged in a mildly trabecular pattern.Tumor cells are strongly positive for neuroendocrine markers synaptophysin (B) and chromogranin (C), shown at 100x magnification.