[Scintigraphy with iodine-131 metaiodobenzylguanidine in the study of paraganglioma. Comparison between benign and malignant tumors].

In order to evaluate 131I metaiodobenzylguanidine (MIBG) uptake in patients with benign or malignant paragangliomas, 28 patients (14 men and 14 women, mean age 37 +/- 10 years) with benign (no. = 15; group 1) or malignant (no. = 13; group 2) tumors underwent MIBG scintigraphy. A total of 110 lesions (20 benign and 90 malignant) were studied. In all patients histologic disease confirmation was obtained. MIBG uptake was quantified on 48 hours' images (Kodak NMC-1 films) using a photographic densitometer. The optical densities of tumor and adjacent or contralateral normal tissue were used to calculate the MIBG uptake intensity ratio for each lesion. In group 1, all patients exhibited 1 or 2 lesions with abnormal MIBG uptake. In group 2, all patients had 1 to 28 abnormal foci of MIBG uptake. In the patients with 2 or more lesions, the average MIBG uptake intensity ratio was calculated. MIBG uptake intensity ratio was significantly higher in malignant than in benign paragangliomas (5.2 +/- 2.4 vs 2.9 +/- 1.4, p < 0.01). Since MIBG uptake in paragangliomas reflects the intratumoral concentration of catecholamines, higher MIBG uptake in malignant lesions suggests a greater amount of stored catecholamines in these tumors. In conclusion, 131I MIBG scintigraphy may be useful to distinguish benign from malignant paragangliomas.