Multiple endocrine neoplasia type 2 (MEN 2) was excluded by normal findings of the thyroid gland and neck ultrasound scan, normal serum level of carcinoembryonic antigen (CEA) and calcium, parathyroid hormone for medullary thyroid carcinoma, and parathyroid hyperplasia respectively. Here, CEACAM5 is linked to multiple endocrine neoplasia type 2.