Pheochromocytoma

00:00 Paragangliomas are tumors composed of chromaffin cells.

00:05 80% of Intra-adrenal pheochromocytomas are paragangliomas.

00:10 Pheochromocytoma and extra-adrenal sympathetic paragangliomas almost always secrete catecholamines.

00:17 These include norepinephrine, epinephrine, and dopamine.

00:22 Although catecholamine-secreting tumors are rare overall, they are found in 0.5% of patients with hypertension.

00:31 Pheochromocytomas account for 5% of adrenal incidentalomas.

00:37 An incidentaloma is a radiographic term for a mass incidentally found on imaging.

00:43 Most pheochromocytomas secrete norepinephrine resulting in episodic or sustained hypertension as was present in our case.

00:52 Orthostatic hypotension can also be seen and likely reflects low plasma volume.

00:57 Symptoms as described include palpitations, tremor, pallor, and anxiety.

01:03 Less commonly, these patients can present with papilledema, diabetes mellitus, and cardiomyopathy.

01:09 Most of these manifestations are from elevated levels of blood pressure.

01:13 Approximately, 10% of pheochromocytomas and 20 to 50% of paragangliomas are malignant.

01:21 Pheochromocytomas are seen with multiple endocrine neoplasia syndromes.

01:27 Type 2A and 2B MEN syndromes include neurofibromatosis type 1 and Von Hippel-Lindau syndrome.

01:35 Let’s review some of the multiple endocrine neoplasia syndromes.

01:40 MEN 1 is caused by the inheritance of one mutated allele with a somatic mutation in other allele and leads to neoplasias.

01:48 The most common presentation is with a parathyroid adenoma, often multiple.

01:53 To confirm the diagnosis of MEN 1, this must be associated with pancreatic islet cell tumors or enteric tumors like a gastrinoma or an insulinoma.

02:04 Pituitary adenomas may also occur.

02:07 Other associations include carcinoid tumors and adrenocortical adenomas.

02:12 MEN 2A most commonly manifests with medullary thyroid carcinoma in association with a pheochromocytoma which is often multifocal as well as parathyroid hyperplasia.

02:24 MEN 2B manifests with medullary thyroid carcinoma.

02:29 But here, although also associated with pheochromocytomas is also accompanied by mucosal neuromas, gastrointestinal ganglioneuromas, and patients may have a Marfanoid body habitus.

02:42 Returning now to confirming the diagnosis of pheochromocytoma, the excessive secretion of catecholamines or their metabolites as measured in the plasma or urine will help.

02:53 Evaluation is recommended for all incidentally noted adrenal masses or in the setting of hereditary pheochromocytoma or paraganglioma syndromes.

03:04 The sensitivity of plasma free metanephrines is the highest of any screening test in endocrinology at 96-100%.

03:12 However, the specificity is relatively low at 85-89%.

03:17 Bear in mind that the pretest probability based on the patient’s presentation in terms of signs and symptoms can improve this.

03:26 Plasma free metanephrines will reliably exclude a pheochromocytoma when negative.

03:32 But further testing is needed to confirm the diagnosis unless the result is markedly abnormal, often in the range of four times the upper limits of normal.

03:43 Imaging follows the biochemical diagnosis for radiographic localization.

03:49 Because most catecholamine-secreting tumors are located in the abdomen, a CT or MRI of the abdomen is the best place to start.

03:58 If negative, an Iodine-123 MIBG scan can be performed.

04:04 Adjunctive diagnostic tests are MRI of the chest and the neck region if you have not identified the tumors within the abdomen.

04:17 Laparoscopic adrenalectomy is the preferred treatment for pheochromocytoma except in the case of a large or malignant tumor where an open adrenalectomy is required.

04:28 Long-term follow up is needed for pheochromocytoma and paragangliomas due to difficulty distinguishing benign from malignant tumors.

04:37 Metastases have been reported after 20 years of the diagnosis.

04:42 In addition to routine clinical surveillance, annual measurements of plasma or urine metanephrines is indicated to assess for a current or metastatic disease.

04:53 Metastatic disease is managed with additional surgery and MIBG therapy as well as chemotherapy and/or radiotherapy.