A case of multiple endocrine neoplasia type 2B undiagnosed for many years despite its typical phenotype.

We report the case of a 24-yr-old man with a typical phenotype of multiple endocrine neoplasia type 2B (MEN 2B). The patient had previously undergone minor surgery to remove multiple tumors on the lip, but he had no further examinations. MEN 2B was suspected owing to characteristic multiple ganglioneuromatosis when the patient presented with a goiter associated with high levels of plasma calcitonin and CEA. Aspiration biopsy cytology revealed medullary thyroid carcinoma (MTC), and abdominal computed tomography and nuclear scanning with metaiodobenzylguanidine revealed bilateral adrenomedullary tumors. Adrenomedullary function tests showed high levels of serum and urinary fractionated catecholamines, and genetic analysis showed a point mutation in the codon 918 (M918T) of the RET gene. The patient was diagnosed with MEN 2B and underwent right adrenalectomy and total thyroidectomy. No distant metastasis of the MTC was noted although MEN 2B had remained undiagnosed since the ganglioneuromatosis was first noticed. MEN 2B is a rare hereditary disorder, but the occurrence of characteristic ganglioneuromatosis was quite helpful in making the diagnosis.