Endocrine Abstracts

Multiple endocrine neoplasia type2A (MEN 2A) is a syndrome of familial cancers characterized by medullary thyroid carcinoma (MTC), pheochromocytoma and hyperplasia of the parathyroid glands. RET protooncogene is the responsible gene for MEN 2A; in more than 96% of MEN 2A families mutations in RET exon 10 or exon 11 are identified. Herein we report a MEN 2A case affected by a mutation (Gly⁵³³Cys) in exon 8. A 66-yr-old male patient was referred to our Department due to bilateral adrenal nodules, revealed incidentally on a computed tomography of the abdomen. Patient’s family history was remarkable for pheochromocytoma in his mother. On physical examination there were no features of von Hippel-Lindau disease (VHL) or neurofibromatosis type 1(NF1). Biochemical evaluation (elevated normetanephrines and metanephrines excretion) and findings of the adrenals’ magnetic resonance imaging (hyperintense adrenal nodules on T₂-weighted image) were compatible with the diagnosis of bilateral pheochromocytomas. The patient underwent laparoscopic bilateral adrenalectomy and histological examination confirmed the preoperative diagnosis of pheochromocytoma. Absence of phenotypic characteristics of VHL or NF1 and elevated basal and stimulated by pentagastrin serum calcitonin levels raised the possibility of MEN 2A syndrome. Total thyroidectomy was performed and histological examination showed the presence of MTC. Genetic testing for the presence of a RET mutation was also recommended. Direct sequencing of exon 8 from patient’s genomic DNA revealed the mutation c.1597G–>T (Gly533Cys). So far, the above missense point mutation has been associated with familial MTC (FMTC) but, to the best of our knowledge, mutations in exon 8 have never been identified in a MEN 2A case. In conclusion, in patients with clinical suspicion of MEN 2A syndrome the analysis of RET exon 8 should be considered when routine evaluation of mutations in exons 10, 11 and 13 is negative.