A 29-year-old man comes to the emergency department complaining of palpitations, sweating, and severe headache. His symptoms resolve spontaneously by the time he is evaluated. He has had at least 2 similar episodes during the past 2 months. The patient's family history is unremarkable. He does not use tobacco, alcohol, or illicit drugs. His primary care provider saw him after the first episode and prescribed an anxiolytic medication. However, the patient felt drowsy at his job and stopped the medication. Physical examination shows a thin man who appears anxious and diaphoretic. The thyroid is normal to palpation without any obvious nodules. His temperature is 36.7 C (98 F), blood pressure is 126/84 mm Hg, pulse is 86/min, and respirations are 16/min. During his prior emergency department visit for an identical episode, his blood pressure was 150/100 mm Hg and pulse was 120/min. The laboratory results at that time showed normal thyroid function tests. Endocrine studies yield results highly suspicious of a neuroendocrine tumor. Which of the following is the best next step in management of this patient?

Question

A 29-year-old man comes to the emergency department complaining of palpitations, sweating, and severe headache.  His symptoms resolve spontaneously by the time he is evaluated.  He has had at least 2 similar episodes during the past 2 months.  The patient's family history is unremarkable.  He does not use tobacco, alcohol, or illicit drugs.  His primary care provider saw him after the first episode and prescribed an anxiolytic medication.  However, the patient felt drowsy at his job and stopped the medication.  Physical examination shows a thin man who appears anxious and diaphoretic.  The thyroid is normal to palpation without any obvious nodules.  His temperature is 36.7 C (98 F), blood pressure is 126/84 mm Hg, pulse is 86/min, and respirations are 16/min.  During his prior emergency department visit for an identical episode, his blood pressure was 150/100 mm Hg and pulse was 120/min.  The laboratory results at that time showed normal thyroid function tests. Endocrine studies yield results highly suspicious of a neuroendocrine tumor.  Which of the following is the best next step in management of this patient?

Quizplus · Accepted Answer

Explanation: 11ec2b69_bed6_ef5c_8f63_17e5547c412f_MD0005_00 Abdominal imaging is the next step for localizing a pheochromocytoma after biochemical confirmation of the tumor. Both CT and MRI are highly sensitive for localizing pheochromocytomas, which are usually located in the adrenal glands. Clinically active pheochromocytomas are typically >4-4.5 cm in diameter and have a high tissue density on CT scan (generally 40-50 Hounsfield units). Larger tumors are more likely to have central necrosis and calcification. MRI usually shows high intensity on T2-weighted images. Patients with negative abdominal imaging usually require further testing such as the metaiodobenzylguanidine (MIBG) scan, which is a functional scintigraphy with I¹²³ labeled MIBG (Choice C). MIBG resembles norepinephrine, is taken up by adrenergic tissue, and can detect tumors not detected by CT or MRI. In addition, MIBG is also performed in patients with large tumors (>5 cm diameter) as they have a higher risk of malignancy and possible extra-adrenal disease. Younger patients and those with a familial disorder also require MIBG after initial CT or MRI as they have a higher risk of extra-adrenal and multiple tumors. ¹²³ (Choices A and E) Removal of the tumor is performed only after localization, adequate preoperative control of blood pressure for 10-14 days with an alpha blocker, and intravascular fluid volume repletion with liberal fluid and salt. Intraoperative complications are much higher with inadequate preoperative alpha blockade and intravascular fluid deficiency. Beta blockers are given only to patients with adequate and complete alpha blockade. Beta-blocking agents started before alpha blockade can lead to paradoxical increase in blood pressure. (Choice B) Chromogranin A (CGA) is stored and released from dense-core secretory granules of neuroendocrine cells and is elevated in nearly 80% of patients with pheochromocytoma. However, elevated CGA levels are not specific for pheochromocytoma and can be elevated in other neuroendocrine tumors (eg, carcinoid) or in patients with mild renal insufficiency. CGA is sometimes used in addition to measuring catecholamine and metanephrine levels in patients with possible drug interference to biochemical testing. Educational objective: Abdominal imaging (CT or MRI) is the next step for localizing a pheochromocytoma after biochemical confirmation of the tumor. Patients with negative abdominal imaging usually require further testing, such as the metaiodobenzylguanidine scan. Removal of the tumor is performed only after adequate preoperative control of blood pressure for 10-14 days with an alpha blocker, and intravascular fluid volume repletion with liberal fluid and salt. Beta blockers are given only to patients with adequate and complete alpha blockade. References: Phaeochromocytoma. (http://www.ncbi.nlm.nih.gov/pubmed/16112304) The utility of metaiodobenzylguanidine (MIBG) scintigraphy in patients with pheochromocytoma. (http://www.ncbi.nlm.nih.gov/pubmed/18193324)

A 29-Year-Old Man Comes to the Emergency Department Complaining of Palpitations