Abstract


Mario Carlos Rivera*
UNM, ALBUQUERQUE, NM

Background:
1) Diagnosis of an intraabdominal paragangliomas presenting as an incidental mass on imaging is challenging.
2) Parasympathetic paragangliomas of the head and neck have been associated with hypoxia. However no correlation has been reported with sympathetic paragangliomas.

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Mario Carlos Rivera*
UNM, ALBUQUERQUE, NM

Background:
1) Diagnosis of an intraabdominal paragangliomas presenting as an incidental mass on imaging is challenging.
2) Parasympathetic paragangliomas of the head and neck have been associated with hypoxia. However no correlation has been reported with sympathetic paragangliomas.

Clinical case: A 66 year-old Hispanic male with hypertension on Lisinopril, hydrochlorothiazide and diltiazem. Presented to the ED for a 1-week history of bilateral flank pain. His past medical history is significant for oxygen dependent COPD, DM 2, hyperlipidemia, chronic low back pain. His father and grandfather have hypertension, denies other history of neoplastic or endocrine diseases. His physical exam was significant for hypertension at 200/110. Labs including CBC, BMP and UA were within normal limits. Abdominal CT scan showed a solitary 2x2cm periaortic mass above the origin of the inferior mesenteric artery (IMA). Reported as possible GI leiomyoma, lymphoma or GI stromal tumor.

A biopsy was initially contemplated. However, its characteristic location above the origin of the IMA (Organ of Zuckerkandl) paraganglioma was considered. Therefore, before proceeding with biopsy, an MIBG scan was performed. It showed increased radiotracer uptake of the mass, without increased uptake on the adrenal glands.
Serum cathecolamines testing showed a slightly increased total amount of catecholamines: 1127 pg/ml (nl <1125 pg/ml), mostly due to norepinephrine 1113 pg/ml (nl <1109 pg/ml) and dopamine 44 pg/ml (nl <20 pg/ml). Serum metanephrines showed a markedly elevated total level at 1161 pg/ml (nl <148 pg/ml), composed entirely by free normetanephrines. 24 hour urine revealed an elevated metanephrine/creatinine ratio was elevated at 910 pg/mg (<600pg/mg).

He was started with doxazosin 1mg, with improved BP control. Has not underwent surgical resection given severe COPD.
The location of a paraortic mass hints on its nature: the origin of the IMA, the organ of Zuckerkandl, sis suggestive of a catecholamine producing tumor (1).

Conclusions:

  • The catecholamine hypersecretion profile is helpful on evaluating paragangliomas as compared to pheochromocytomas: Paragangliomas are unlikely to secrete epinephrine (cortisol needed as a cofactor of PNMT for synthesis), being norepinephrine the main catecholamine secreted it is expected for normetanephrine, its metabolite, to be increased as well. Dopamine is usually elevated on familial paraganglioma due to SDHb (succinate dehydrogenase b) mutation, as compared to spontaneous ones .
  • Attempts to do preoperative biopsy of a paraganglioma may cause severe hypertension and 70% of biopsy related complication were reported on series of cases. It is therefore contraindicated.
  • Chronic hypoxic states, especially high altitude, have been linked to paraganglioma on genetically predisposed hosts (germline SDH mutation), through the HIF-2a/VHL mechanism.
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