Fellow Albany medical Center Albany, New York, United States
Introduction : Pheochromocytoma is a rare benign catecholamine-secreting tumor, which originates from the adrenal gland. It is known for a wide range of clinical manifestations and can mimic other difficult-to-diagnose diseases. Here, we describe a case of surgically confirmed pheochromocytoma that was presented as a lipid-rich adenoma on CT.
Case(s) Description : A 60-year-old woman with history of headaches and uncontrolled hypertension was referred to us for further evaluation of a 2.9 cm left adrenal nodule. Biochemical work-up was negative for primary hyperaldosteronism or Cushing’s syndrome. Plasma normetanephrine was high at 2.71 nmol/L (nl. 0.00 - 0.89). 24-hr urinary normetanephrine was also elevated at 852 ug/g (nl. 0 - 400). Abdominal CT with and without contrast revealed a 2.9 x 1.6 cm left adrenal nodule with -8.6 Hounsfield units (HU) and 61% of absolute washout, which were not suggestive of pheochromocytoma. She was pre-treated with doxazosin with significantly improved blood pressure. Subsequently she underwent robotically assisted laparoscopic left adrenalectomy. Surgical pathology was consistent with a well-differentiated pheochromocytoma.
Discussion : Pheochromocytomas are often well-defined masses with attenuation values approximately 30–40 HU. CT is the most common imaging method used in the diagnosis of pheochromocytomas. In most cases, characteristic CT findings with positive biochemical tests are sufficient for the diagnosis. Attenuation values on CT of less than 10 HU are usually adrenal adenomas. Pheochromocytomas can infrequently contain fat that could result in low attenuation on CT. Although extremely rare, providers should have a high level of suspicion for a pheochromocytoma in patients with a history of uncontrolled hypertension even if they have a lipid-rich nodule on imaging.
