Retroperitoneal paragangliomas are rare and easily misdiagnosed. These tumors are often discovered incidentally during imaging studies performed for other reasons. Paragangliomas are tumors that originate from extra-adrenal medullary neural crest derivatives. Most of them are located in the head and neck, but can be found in various body sites, including the thoracic cavity, abdomen, pelvis, and bladder. ¹

Periampullary cancers include adenocarcinomas arising from the pancreas, ampulla of Vater, duodenum or distal common bile duct. The exact site of origin of periampullary tumors is often difficult to ascertain preoperatively. ²

We report the case of a patient who had a retroperitoneal paraganglioma manifested as an abdominal mass with concurrent periampullary carcinoma; it is the first report of such a concurrency.

An 81-year-old woman with fit physiologic condition, was admitted to our institution in Isfahan, Iran, in 2012, because she experienced progressive abdominal fullness and dull epigastric pain for a few months. Her past medical history was unremarkable. Her blood pressure and heart rate were within normal limits and liver enzymes including serum glutamic oxaloacetic transaminase (SGOT), serum glutamic-pyruvic transaminase (SGPT), alkaline phosphatase and gamma glutamyl transferase showed increased values. Bilirubin level, Carcinoembryonic antigen and cancer antigen 19-9 levels were within normal limits.

In the abdominal examination a large mass on upper paramedian, left side was touched. A computed tomography (CT) scan of the abdomen demonstrated a large retroperitoneal solid-cystic mass and significant dilation of gallbladder, intra and extra hepatic and pancreatic ducts Figure 1. Figure 1

Abdominal CT revealed large retroperitoneal mass

Pheochromocytomas and extra-adrenal paragangliomas are very rare tumors that arise from the neural crest tissue. These tumors are functional in more than half of cases, and patients commonly present with symptoms, such as palpitation, headache, and sweating that are related to excess catecholamine secretion. ¹ About 70% of sympathetic paragangliomas are intra-abdominal, usually found in the perinephric and paraaortic spaces. The remaining 30% are located in the thorax. Malignant retroperitoneal paragangliomas range from 30% to 50%. ³ Paragangliomas metastasize approximately in 20-42% of the cases. ⁴ Our case was a non-functional retroperitoneal paraganglioma.

The non-secretory type most commonly presents as an abdominal pain or mass; ⁵ a large proportion of these tumors are incidentally discovered in normotensive patients during imaging evaluation for other reasons. ⁶

They are commonly located in the para-aortic region and they may be confused with other retroperitoneal tumors, especially pancreatic tumors. Magnetic Resonance Imaging (MRI) is more sensitive than CT in detecting extra-adrenal tumors. Scintigraphy with 123-I labeled Meta-Iodo-Benzyl-GuanidineMIBG offers superior specificity than CT and MRI imaging. ⁴

Besides the use of imaging studies for diagnosing paragangliomas, assessment of the plasma normetanephrine level or of the metanephrine and catecholamine levels via 24 h urine collection can help physicians make the actual diagnosis. In our patient′s case, diagnosing the paraganglioma before surgery was not clear; so, we did not analyze the relevant serum marker. Complete surgical excision is the treatment of choice for extra-adrenal paragangliomas. ¹

A definitive diagnosis can be made only by histology and there are no histologic criteria to distinguish between benign and malignant tumors. Only the appearance of distant metastases, metastases at a site where paraganglionic tissue is not usually found or local recurrence can confirm that the tumor is cancerous. However, total excision is the basis of curative treatment because these tumors are potentially malignant. ⁷

The precise origin of a periampullary adenocarcinoma is often difficult to determine even with standardized histopathologic evaluation, particularly if the tumor is large and involves more than one potential site of origin. ³ , ⁸ Tumor destruction of normal periampullary anatomy, and presence of epithelial dysplasia in more than a single periampullary compartment, occurs frequently. ⁹ However, in our case, according to early detection, the precise site of the neoplasm was clear.

Surgeons in treating patients with these tumors have favored an aggressive method of resection to benefit these patients with better prognosis. Although the perioperative outcomes for these tumors are similar, the long-term survival has traditionally varied. ⁸ , ¹⁰ , ¹¹ It is unknown why outcome varies for adenocarcinomas arising from anatomic sites in such close proximity. ²

Of the 242 patients with resected periampullary adenocarcinoma, 149 (62%) were pancreatic primaries, 46 (19%) arose in the ampulla, 30 (12%) were in distal bile duct, and 17 (7%) were duodenal cancers. The tumor-specific 5 year actual survival rates were 15% for pancreatic, 39% for ampullary, 27% for distal bile duct, and 59% for duodenal cancers. Among patients with periampullary adenocarcinoma treated by pancreaticoduodenectomy, those with duodenal adenocarcinoma are most likely to survive long-term. ⁸

Developments in the broad field of molecular genetics may allow for earlier detection of periampullary neoplasms, perhaps using gene-based diagnostic testing of easily accessible clinical specimens such as blood, duodenal juice or stool. Furthermore, progress in adjuvant therapies, maybe incorporating new combinations of chemotherapy, radiation therapy, and immunotherapy, would result in improvements in disease-free and overall survival rates. ⁸

In conclusion, Concurrent duodenal cancer and a retroperitoneal paragangliomas is an in experienced event in the clinic and pathologic fields and it makes pre-operative diagnosis of such masses difficult or even impossible, especially when the paraganglioma is non-functional.