Abstract
Multiple endocrine neoplasia (MEN) type 2a (Sipple's syndrome) is characterized by medullary thyroid carcinoma and pheochromocytoma, and in a smaller percentage of cases, multiglandular parathyroid hyperplasia. This autosomal-dominant syndrome is due to a mutation in the rearranged during transfection (RET) proto-oncogene located on chromosome 10cen-10q11.2 and rarely complicates pregnancy. We present an unusual case in a patient with an enlarged thyroid with sonographic findings characteristic of thyroid cancer, which led to diagnosis and subsequent management of RET proto-oncogene-positive MEN type 2a complicating pregnancy.