Endocrine Abstracts

Objective: To evaluate pheochromocytoma that occurs in Saudi patients with MEN 2A

Patients and methods: Of 44 patients belonging to 5 MEN 2A families, 14 (31.8%) presented with pheochromocytoma. The following variables have been studied: clinical and diagnostic data (age, mutation, clinical features, and laboratory studies included measurements of 24-h urinary catecholamines, epinephrine, metanephrine, norepinephrine, dopamine, vanillylmandelic acid, and plasma metanephrine, norepinephrine, and epinephrine. Laboratory studies were considered abnormal in cases where these values were elevated. Tumor location and dimensions were obtained from computerized tomography (CT) scan and iodine-131 meta-iodobenzylguanidine (MIBG) scintigraphy results. The means of diagnostic, clinical, or genetic screening were also studied as well as surgical treatment and follow-up and recurrence. The mean follow-up time was 7 years (range: 12–108 months).

Results: The mean age of the 14 patients was 33.5 years (range: 12–52 years); 10 were women. Most (71.4%) mutations were found in exon 11. The most frequent mutations were Cys634Tyr (in eight cases (57.1%)) and Cys634Arg (in three (21.4%)). The diagnosis of pheocromocytoma was made after the diagnosis of MTC in seven cases (50%), simultaneously in five (35.7%), and prior in the two remaining cases (14.3%). At the time of diagnosis eight patients (57.1%) were asymptomatic and six (42.9%) had clinical features related to pheochromocytoma. The most useful isolated laboratory studies were measurements of plasma metanephrine followed by 24-h of urinary metanephrines (82%). The CT scan did not provide a correct diagnosis in one patient with bilateral lesions, and one patient with a unilateral tumor was not diagnosed by MIBG. The combination of CT scan and MIBG diagnosed 100% of cases. The pheochromocytoma was bilateral in two cases. The most commonly used medication for preoperative treatment was phenoxybenzamine, which was utilized in 11 patients (78.6%) and prazosin was used in three patients (21.4%). In two patients (14.2%), beta-blockers were administered in addition to an alpha-blocker. The length of preoperative management was variable with a range of 2–8 weeks.

A laparascopic approach was used in nine cases and a laparotomy in five. The mean tumor size was 3.5 cm (range: 1.5–10 cm). There was a greater frequency of pheochromocytoma in those subjects who had the Cys634Arg mutation (P<0.03). In addition, the Cys634Arg mutation is more frequent in bilateral cases. There are no prognostic factors for recurrence.

Conclusions: Pheochromocytoma in MEN 2A is related to the type of mutation, which can be early onset and is frequently asymptomatic. Its diagnosis requires catecholamines determinations as well as a CT scan. Laparoscopic adrenalectomy is the treatment of choice.