Pheochromocytoma

Key Features

• Uncommon; however, up to 10% of reported cases occur in pediatric patients

• Tumor can be located wherever chromaffin tissue (adrenal medulla, sympathetic ganglia, or carotid body) is present

• May be multiple, recurrent, and sometimes malignant

• Familial forms include pheochromocytomas associated with the dominantly inherited neurofibromatosis type 1, multiple endocrine neoplasia type 2, and von Hippel-Lindau syndromes, as well as mutations of the succinate dehydrogenase genes

Clinical Findings

• Headache

• Sweating

• Tachycardia

• Hypertension

• Vasomotor instability (flushing and postural hypotension)

• Anxiety

• Dizziness, weakness

• Nausea, vomiting, diarrhea

• Dilated pupils, blurred vision

• Abdominal and precordial pain

Diagnosis

• Serum and urine catecholamines are elevated

• Plasma-free metanephrine is the most sensitive and specific test, although phenoxybenzamine, tricyclic antidepressants, and β-adrenoreceptor blockers can cause false-positive results

• Levels three times the normal range are diagnostic

• Intermediate values may require additional testing with serum and urine catecholamines

• After demonstrating a tumor biochemically, imaging methods including CT or MRI are used to localize the tumor

• Nuclear medicine using functional ligands such as (123) I-MIBG, [¹⁸F]DA positron emission tomography scanning, and somatostatin receptor scintigraphy (with either [¹²³ I]Tyr3-octreotide or [¹¹¹ In] DTPA-octreotide) are useful in further diagnostic evaluation

Treatment

• Laparoscopic tumor removal is the treatment of choice; however, the procedure must be undertaken with great caution and with the patient properly stabilized

• Oral phenoxybenzamine or intravenous phentolamine is used preoperatively

• Profound hypotension may occur as the tumor is removed but may be controlled with an infusion of norepinephrine, which may have to be continued for 1–2 days