Metastatic Medullary Thyroid Carcinoma as a Presenting Feature of Multiple Endocrine Neoplasia 2B: A Case Report and Literature Review

Multiple Endocrine Neoplasia type 2B (MEN2B) is an autosomal dominant disorder characterized by Medullary Thyroid Carcinoma (MTC) and pheochromocytoma. MTC occurs in almost all MEN2B patients. The tumor develops at an earlier age and is aggressive. Surgery is often not curative for this condition. Death from MTC occurred in 50% of patients with MEN2B. Thus, early diagnosis and prevention are crucial in this regard. Thyroidectomy, as early as the neonatal period, may be indicated in patients with MEN2B identified by genetic screening.

We reported a 24-year-old male presented to the emergency department with dyspnea for the past 3 months. There was a nodule 3*3 cm in the Right Lower Lobe (RLL) of the thyroid gland. Non-contrast Computer Tomography (CT) scan of the lung revealed multiple nodular lesions compatible with metastasis. The Fine Needle Aspiration (FNA) cytology of the thyroid nodule indicated that the features of medullary thyroid carcinoma were positive stains in Immunohistochemistry (IHC) for calcitonin. A diagnosis of pulmonary metastatic medullary thyroid carcinoma, as a presenting feature of MEN2B, was made. The
patient was treated with Vandetanib.

In the reported MEN2B patient, MTC occurred in the early stages of life and was
multifocal. Thus, it is crucial to diagnose medullary thyroid cancer at the early stages of the disease.