[Incidental diagnosis of medullary thyroid carcinoma (MTC) after performing 123I-metaiodobenzylguanidine (123I-MIBG) gammagraphy]. / Diagnóstico de carcinoma medular de tiroides (CMT) de forma casual tras realización de gammagrafía 123I-metayodobencilguanidina (123I-MIBG).

UNLABELLED: The objective of this clinical note is to emphasize diagnostic efficiency of 123I-MIBG scintigraphy in the initial diagnosis and follow-up of medullary thyroid carcinoma within MEN2. MATERIALS AND METHODS: We present the case of a patient who, during a scintigraphic study with 123I-MIBG for the diagnosis of pheochromocytoma, was unexpectedly found to suffer from medullary carcinoma of the thyroid. Prior to performing the test, we proceeded to block uptake into the thyroid gland through the administration of Lugol. We carried out the scintigraphic study by intravenously injecting 370 MBq 123I-MIBG. RESULTS: A pathological uptake of the radiopharmaceutical compound over the right suprarenal gland, and unexpectedly, over the thyroid gland was detected, thus confirming the existence of medullary carcinoma of the thyroid in this patient, and obtaining the diagnosis of Type MEN2A polyglandular syndrome. CONCLUSIONS: From our experience, we can manifest the value of scintigraphy using 123I-MIBG in the diagnosis and localization of medullary carcinoma of the thyroid. Furthermore, it is indicated in patients suspected of MEN, since it makes it possible to reach a diagnosis of this kind of syndrome through the performance of just one test.