Pheochromocytoma Clinically unsuspected pheochromocytoma

ABSTRACT

PURPOSE: Pheochromocytoma is a catecholamine-secreting tumor that arises from the chromaffin cells of the sympathoadrenal system and presents with the typical symptoms of palpitation, diaphoresis, head ache, and hypertension. Some pheochromocytoma may be discovered during computed tomography of the abdomen while evaluating the abdomen and may be clinically unsuspected before surgery. The aim of this study was to analyze the clinical presentation of pheochromocytoma and to identify the charac teristics of clinically unsuspected pheochromocytomas. METHODS: From June 1995 to October 1999, 34 histopathologically confirmed pheochromocytomas were diagnosed at Samsung Medical Center, Seoul, Korea. The records of all 34 patients, who had undergone a surgical resection for pheochromocytoma and paraganglioma, were reviewed for demographic information, presenting signs and symptoms, bio chemical profiles that led to the laboratory diagnosis of pheochromocytoma, tumor localization studies, associated diseases, preoperative preparation, surgical procedures, and tumor pathology. RESULTS: The most prominent symptoms of pheochromocytomas was palpitation, which was present in 21 (62%) of the 34 cases. Hypertension, headache, and sweating were in 18 (53%), 17 (50%), and 9 (27%) patients, respectively. In 14 (41%) of the 34 patients, the pheochromocytoma were incidentally found exhibiting none of the typical symptoms. Eight (24%) were clinically unsuspected and were undiagnosed prior to surgery. A preoperative diagnosis of either retroperitoneal or pancreatic mass was made in six cases (18%), and a diagnosis of a nonfunctioning adrenal mass was made in two (6%). These eight patients underwent surgery without any preoperative pharmacological treatment. Sporadic cases accounted for 85% of the patients (29 patients), and associated conditions included MEN 2A in four (12%) and MEN 2B in one (3%).The sensitivities of the urinary evaluation were metanephrine 85%, norepinephrine 81%, epinephrine 73%, and vanillylmandelic acid (VMA) 73%. The combination of urinary metanephrine and VMA had a diagnostic sensitivity of 92%. The sensitivities of the localization modalities were CT 100%(33/33), MRI 100% (3/3). USG 94.8% (18/19), MIBG 70% (7/10). Four of the 8 patients who received no preoperative preparation and 10 of the 26 patients who received phenoxybenzamine daily for at least 2 weeks) had intraoperative hypertension or arrythmia. One patient received a laparoscopic adrenalectomy. The rest of the patients underwent surgery through open transabdominal incision. The mean tumor diameter of the malignant pheochromocytomas was 10.8 cm (range from 4.5 to 16 cm), and that of the benign pheochromocytoma was 6.1 cm (range from 3 to 10 cm) showing marked differences between two groups. This suggests that malignant tumors tend to be larger than benign tumors. Of the 4 malignant cases, recurrent disease occurred at the site of the original tumor in 1 patient, metastasis didnt occur in any case. CONCLUSION: High index of suspicion for a pheochromocytoma must be maintained in patients with retroperitonal and abdominal masses or isolated hypertension and in patients with multiple endocrine neoplasms. The readily available, sensitive assays for plasma and urinary catecholamines and their me tabolites and the newly developed modern imaging techniques, such as CT and I-131-MIBG, when used together, may help inmaking correct diagnosis of pheochromocytoma in patients without paroxysmal symptoms or hypertension.