Thyroid uptake of MIBG in Sipple's syndrome

The use of the adrenomedullary tracer metaiodobenzylguanidine (MIBG) in the localization of medullary carcinoma of the thyroid (MCT) is based on the embryologic relationship of the APUD cell series. The authors report the results obtained in six patients with MCT: two had Sipple's syndrome and four sporadic forms of the disease. MIBG uptake by the CMT was observed in both cases of Sipple's syndrome and in only one of the other cases. Scintigraphic detection seems to depend on the clinical features, the size of the tumour and also on the part played by its secretory function. MCT would thus appear to be more frequently visualized by MIBG in cases of Sipple's syndrome than in sporadic cases. The procedure therefore seems useful in the diagnosis, follow up and even in the treatment of MCT.