Small Pheochromocytomas Research Articles

The Raf-1 pathway: a molecular target for treatment of select neuroendocrine tumors?

Neuroendocrine (NE) tumors such as medullary thyroid cancer, carcinoid, small cell lung cancer and pheochromocytoma are metastatic in nature, and secrete biogenic amines and hormones. In this review, we will discuss the possibility that activation of the Ras/Raf signaling pathway may be a therapeutic target for patients with select NE tumors. In-vitro activation of Raf-1 in NE tumors either by expression of the ectopic catalytic domain of Raf-1 or by a pharmacologic drug, ZM336372, resulted in growth inhibition. In addition, activation of the Ras/Raf pathway led to a significant reduction in NE markers such as serotonin, chromogranin A and calcitonin. These data support development of Raf-1-activating compounds for treatment of patients with NE tumors of selective subtypes.

Pheochromocytoma of the Urinary Bladder

Paraganglioma of the urinary bladder is rarely encountered. It accounts for less than 0.5% of bladder tumors 1 and only 1% of all pheochromocytomas. Pheochromocytomas that arise outside the adrenal gland are termed extra-adrenal pheochromocytomas or paragangliomas. The most common signs and symptoms are hypertension and hematuria. 2 If the presence of pheochromocytoma is suspected on clinical grounds, imaging studies are useful in localizing the tumor. 3 Computed tomography (CT) is frequently used because of its high sensitivity for detecting adrenal (94%) and extra-adrenal (82%) pheochromocytomas. Magnetic resonance imaging (MRI) is more sensitive than CT for detecting small extra-adrenal pheochromocytomas because of its inherent tissue contrast resolution.3 The [ 1 3 1 I]metaiodobenzylguanidine (MIBG) scan is regarded to be highly specific for bladder pheochromocytoma; however, its use is limited because of its expense and restricted availability. 4 In this report, we have described the clinical, laboratory, imaging, radionuclide, and histopathologic features of this uncommon tumor. Thus, in patients with similar unusual symptoms and increase in blood pressure with micturition, a clinical diagnosis of pheochromocytoma of the urinary bladder must be considered. Imaging studies such as ultrasonography (USG), CT, MRI, and [ 1 3 1 I]MIBG scans will help in confirming the diagnosis and localizing the tumor. Pheochromocytoma of the urinary bladder is a rare tumor with striking and unusual manifestations.

Section 3. Adrenal: Laparoscopic adrenalectomy for pheochromocytoma: a literature review

Laparoscopic adrenalectomy has become the standard treatment for benign adrenal tumors, providing minimal invasiveness and early recovery. In the case of pheochromocytomas, special attention should be paid perioperatively to prevent excessive hypertension or hypotension. The protocol should include sufficient preoperative medication with alpha 1 blockers, early ligation of the adrenal vein, and minimal handling of the tumor itself. A literature review of 227 laparoscopic adrenalectomies for pheochromocytomas revealed that the perioperative data, including the operative time, blood loss, and hemodynamic status, were similar or slightly better in the laparoscopic procedures as compared to the open procedures, although the convalescence period was significantly shorter in the laparoscopic surgery. The majority of surgeons prefer the transperitoneal approach for pheochromocytomas, although some authors use the retroperitoneal approach successfully. A comparison of the perioperative data from laparoscopic surgeries for pheochromocytomas versus those for other adrenal tumors showed that the former had slightly higher demands to complete the procedure safely. In the treatment of familial pheochromocytoma due to multiple endocrine neoplasia type 2 or von Hippel–Lindau disease, a cortical-sparing adrenalectomy can be safely performed laparoscopically. In conclusion, laparoscopic adrenalectomy is the standard for small pheochromocytomas, with a high success rate when the procedure is performed by experienced surgeons.

Influence of Tumor Size on Anesthetic Management for Pheochromocytoma Resection

The relationship between tumor size and the complexity of anesthetic management was studied using several values: plasma catecholamine concentrations, requirement of vasoactive agents, surgical time, blood loss, plasma glucose concentrations, and hemodynamic variables. Ten patients with clinical and laboratory diagnosis of pheochromocytoma were prospectively studied. Each anesthesia was maintained using inhalational anesthetic agents. Control of arterial blood pressure (ABP), heart rate (HR), and pulmonary artery blood pressure (PABP) was attempted with only titrating the inhalational anesthetics and adenosine triphosphate (ATP). If the titration of both the inhalational anesthetic and ATP failed to control ABP, HR, or PABP, then phentolamine, propranolol, trinitroglycerine, or norepinephrine was additionally used. Tumor weight was significantly correlated with amount of blood loss, surgical time, duration of ATP requirement, maximal dose of ATP infusion used, maximal plasma glucose concentration, and plasma total catecholamine concentration. However, the tumor weight was not correlated with hemodynamic variables. Patients who required propranolol generally had a significantly larger tumor than those who did not. In conclusion, surgical removal of large pheochromocytoma required more complicated anesthetic management than that of small pheochromocytoma.

Influence of tumor size on anesthetic management for pheochromocytoma resection.

The relationship between tumor size and the complexity of anesthetic management was studied using several values: plasma catecholamine concentrations, requirement of vasoactive agents, surgical time, blood loss, plasma glucose concentrations, and hemodynamic variables. Ten patients with clinical and laboratory diagnosis of pheochromocytoma were prospectively studied. Each anesthesia was maintained using inhalational anesthetic agents. Control of arterial blood pressure (ABP), heart rate (HR), and pulmonary artery blood pressure (PABP) was attempted with only titrating the inhalational anesthetics and adenosine triphosphate (ATP). If the titration of both the inhalational anesthetic and ATP failed to control ABP, HR, or PABP, then phentolamine, propranolol, trinitroglycerine, or norepinephrine was additionally used. Tumor weight was significantly correlated with amount of blood loss, surgical time, duration of ATP requirement, maximal dose of ATP infusion used, maximal plasma glucose concentration, and plasma total catecholamine concentration. However, the tumor weight was not correlated with hemodynamic variables. Patients who required propranolol generally had a significantly larger tumor than those who did not. In conclusion, surgical removal of large pheochromocytoma required more complicated anesthetic management than that of small pheochromocytoma.