by Michael Lazarus, MD

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    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.

    About the Lecture

    The lecture Pheochromocytoma by Michael Lazarus, MD is from the course Adrenal Gland Disorders. It contains the following chapters:

    • Pheochromocytoma
    • Review of MEN

    Included Quiz Questions

    1. Tremor
    2. Bradycardia
    3. Skin flushing
    4. Papilledema
    5. Episodic hypotension
    1. MEN 1
    2. MEN 2B
    3. Von Hippel–Lindau syndrome
    4. Neurofibromatosis type 1
    5. MEN 2A
    1. Markedly elevated levels of plasma free metanephrines are sufficient to confirm the diagnosis.
    2. When a CT or MRI scan of the abdomen shows negative results, the diagnosis can be safely excluded.
    3. Imaging should be always performed before the biochemical diagnosis.
    4. MIBG screening is preferred over CT scans.
    5. Plasma free metanephrine level is used as the first screening test because of its high specificity.

    Author of lecture Pheochromocytoma

     Michael Lazarus, MD

    Michael Lazarus, MD

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