Imaging of Pheochromocytoma

In this video lecture, we discuss the diagnosis and imaging appearance of pheochromocytoma on ultrasound, CT, MRI, and nuclear medicine studies.

Key points include:

  • Pheochromocytoma is a biochemical diagnosis.
  • Symptoms are variable, and patients may present with headache, palpitations, sweating, hypertension or be asymptomatic.
  • Most cases are sporadic with mean age of presentation in the 40s.
  • Hereditary pheochromocytoma can be seen in the setting of Von Hippel-Lindau disease, multiple endocrine neoplasia (MEN) type II, neurofibromatosis type I, and pheochromocytoma-paraganglioma syndromes associated with succinate dehydrogenase gene mutations.
  • Pheochromocytoma is the “10%” tumor, as approximately 10% are bilateral, extra-adrenal, contain calcification, occur in children, or are malignant.
  • Most pheochromocytomas are solid, but they can also appear as mixed cystic and solid with varying degrees of complexity.
  • The ultrasound appearance is nonspecific, and tumors may contain echogenic hemorrhage or be hypervascular on Doppler imaging.
  • Any mass that enhances to a density greater than 110 HU on an arterial phase CT scan should raise suspicion for pheochromocytoma.
  • On CT, most pheochromocytomas will have noncontrast density greater than 10 HU and absolute washout less than 60%, findings similar to adrenal metastases and adrenocortical carcinoma.
  • However, pheochromocytoma can rarely have noncontrast density less than 10 HU and absolute washout greater than 60%, thus mimicking adrenal adenoma.
  • Studies have shown that pheochromocytoma is not a contraindication to modern nonionic IV contrast media.
  • On MRI, the “light bulb” T2 bright appearance classically associated with pheochromocytoma may or may not be present.
  • If intratumoral hemorrhage is present, pheochromocytomas may show T1 hyperintensity or susceptibility artifact on T1-weighted in-phase images depending on the age of blood.
  • Pheochromocytomas usually do not show signal dropout on T1-weighted opposed-phase images but rarely do and can mimic adrenal adenomas.
  • MIBG scans have nearly 100% specificity for pheochromocytoma and are useful to confirm clinically suspected pheochromocytoma and for detection of metastatic disease.
  • Extra-adrenal pheochromocytomas (paragangliomas) usually occur in abdomen, typically at the organ of Zuckerkandl or in the retroperitoneum.

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