A 61-year-old man with fluctuating hypertension
2. Based on the patient’s clinical presentation and findings on CT, what would be the most likely diagnosis for this incidentally found adrenal mass?
- Adrenocortical adenoma
- Adrenocortical carcinoma
- Metastatic mass
- Pheochromocytoma
Adrenocortical adenoma can present as a small homogeneous mass of variable size, with smooth margins, and rarely containing hemorrhagic tissue or calcifications. The typical density on nonenhanced CT is less than 10 HU. On enhanced CT, it is nonvascular. T2-weighted magnetic resonance imaging (MRI) shows a lesion of the same intensity as liver tissue.6
Adrenocortical adenoma is not classically associated with autologous activity and thus is less likely to explain our patient’s symptoms.
Adrenocortical carcinoma can present as a large heterogeneous mass, usually greater than 4 cm in diameter, with irregular margins and areas of necrosis, hemorrhage, or calcification. The typical density on nonenhanced CT is greater than 10 HU. On enhanced CT, the mass is usually vascular, and T2-weighted MRI will show a lesion more intense than liver tissue.6
Adrenocortical carcinoma is also not classically associated with autologous activity, and so is not likely to explain our patient’s symptoms.6
Metastatic disease can present with masses of variable size, often bilaterally, and occasionally with cysts or areas of hemorrhage. The typical density of metastatic lesions on nonenhanced CT is greater than 10 HU. On enhanced CT, they are usually vascular, and on T2-weighted MRI they are hyperintense.6 The characteristics of the mass and the absence of a primary malignancy on CT of the chest and abdomen do not support the diagnosis of metastatic disease.
Pheochromocytoma is a neuroendocrine tumor of the adrenal medulla that can present as a large heterogeneous mass, greater than 3 cm in diameter, with clear margins and cysts or areas of hemorrhage. Extra-adrenal neuroendocrine tumors are typically called paragangliomas and have features similar to those of pheochromocytoma. The typical density of pheochromocytoma on nonenhanced CT is greater than 10 HU. On enhanced CT, it is usually vascular, and T2-weighted MRI shows a hyperintense lesion. Pheochromocytoma can be biochemically active and thus can cause signs and symptoms that will lead to the diagnosis.6
Other imaging tests may play a role in the evaluation of adrenal masses but are not required for the diagnosis of pheochromocytoma. Functional positron emission tomography using metaiodobenzylguanidine labeled with iodine 123 or-iodine 131 or using the glucose analogue F-18 fluorodeoxyglucose has been used in the initial assessment of pheochromocytoma, with good sensitivity and specificity.7,8
Our patient’s pacemaker-defibrillator precluded him from undergoing MRI.
DIAGNOSIS: PHEOCHROMOCYTOMA
Pheochromocytoma was highly suspected on the basis of the patient’s clinical presentation, and metoprolol was immediately discontinued. He was started on the calcium channel blocker verapamil and the alpha-blocker phenoxybenzamine.
Serum samples were obtained to measure metanephrines, dehydroepiandrosterone, aldosterone, and cortisol, and a 24-hour urine collection was obtained to measure creatinine, dopamine, epinephrine, norepinephrine, cortisol, and metanephrines. Based on the results (Table 1) and on the findings on imaging, the patient was diagnosed with pheochromocytoma. A surgical consultation was obtained, and surgery was recommended.
WHEN DOES PHEOCHROMOCYTOMA CALL FOR SURGERY?
3. Which criterion is most important when determining the need for surgery for pheochromocytoma?
- Findings on fine-needle aspiration biopsy
- Biochemical activity
- Size of the mass
- Bilateral masses
Fine-needle aspiration biopsy can be done when a mass is found incidentally and no evidence of biochemical activity is detected, although it is not an essential part of the diagnostic workup.9 In most cases, the sampling from fine-needle aspiration is not sufficient to achieve a diagnosis.
Biochemical activity is the most important factor when determining the need for prompt surgical intervention. The excess circulating catecholamines have been associated with increased risk of cardiovascular morbidity and death independent of the morbidity associated with hypertension alone.10 Biochemical activity can be independent of the size of the mass, but larger masses typically present with symptoms.
Bilateral masses have been associated with metastatic disease.11 In retrospect, the patient’s history of hypertension and cerebrovascular accident could be associated with the development of a catecholamine-releasing tumor.
A GOOD OUTCOME FROM SURGERY
The patient was continued on phenoxybenzamine for 7 days and responded well to this therapy.
After this preoperative preparation, he underwent laparoscopic right adrenalectomy with excision of a retroperitoneal adrenal mass. His postoperative course was complicated by transient hypotension requiring low-dose vasopressin support for less than 24 hours. He was then restarted on his previous dosage of metoprolol and was discharged home on postoperative day 5 with stable blood pressure. Follow-up 24-hour urine collection 1 month after he was discharged showed normalization of metanephrine, normetanephrine, epinephrine, and norepinephrine levels.
Despite low suspicion for an underlying genetic syndrome, he was referred for genetic testing and was scheduled to have a repeat 24-hour urine collection and imaging in 6 months to follow his enlarged left adrenal gland, which did not appear to be metabolically hyperactive.
4. What is the most common perioperative complication of pheochromocytoma excision?
- Hypoglycemia
- Hypotension
- Hypocortisolism
- Hypertension
- Tachycardia
Hypoglycemia has been observed after removal of pheochromocytoma, as levels of catecholamines (which normally inhibit pancreatic beta cells) decrease and insulin secretion consequently increases.12 Our patient developed hypoglycemia before surgery, not after, and it was likely due to the combination of his antidiabetic therapy, weight loss, and decreased oral intake.
Hypotension is the most common complication in the perioperative period. It is associated with excessive loss of catecholamine secretion. It is usually short-lived but may require aggressive administration of intravenous fluids and use of sympathomimetic agents.
Hypocortisolism is unlikely in patients with pheochromocytoma, but it is likely after removal of adrenocortical adenoma.
Hypertension and tachycardia affect up to 40% of pheochromocytoma patients in some case series.12
