Endocrine Abstracts

JOINT339

Introduction: Multiple Endocrine Neoplasia type 2A (MEN2A) is an autosomal dominant hereditary cancer syndrome caused by a germline mutation in the REarrenged during Transfection (RET) proto-oncogene. Its classic form comprises the association of medullary thyroid carcinoma (MTC), phaeochromocytoma (PHEO), and primary hyperparathyroidism. We report a case of a patient, and his first-degree relatives, diagnosed with MEN2A at the age of 23, who presented bilateral PHEO as the first manifestation.

Objective: To describe the clinical and genetic aspects of a family with MEN2A.

Methods: Review medical records and telemedicine interviews of the index case and his relatives to collect clinical information related to MEN2A.ResultsThe index case was diagnosed with bilateral PHEO and MTC at the age of 22 and 26 respectively, and the allelic variant c.1900T>C;p.Cys634Arg in exon 11, rs75076352 was identified. From there, 13 family members were screened: four siblings, his only son, and eight nephews and nieces. The genetic testing found the allelic variant in eight relatives and, one of them who had not been tested manifested the disease in the follow-up. Of the ten individuals with the syndrome, eight underwent a total thyroidectomy due to MTC, one had suspicious nodules on fine needle aspiration biopsy (FNAB), and another had elevated calcitonin levels at the age of 7. Both were referred for thyroidectomy. The age at diagnosis of MTC ranged from 8 to 35 years. PHEO was diagnosed in six, all of them with bilateral involvement, and the age at diagnosis ranged from 23 to 34 years, except for one case under 20 years of age. Two patients (the index case and his brother) were diagnosed with PHEO before MTC, both had benign FNAB of thyroid nodules. Two cases presented with normocalcemic hyperparathyroidism.

Discussion: In MEN2A, PHEO is frequently diagnosed in the third and fourth decade of life and rarely prior to MTC diagnosis. In this study, we report two patients from the same family with bilateral PHEO as the first manifestation of MEN2A.

Conclusion: PHEO has a strong association with genetic syndromes when diagnosed in young patients, as well as in its bilateral form. Reporting unusual presentations of rare syndromes could help us improve the diagnosis and follow-up of these patients.