Thyroid Cancer (Medullary Carcinoma)
Overview
Plain-Language Overview
Medullary thyroid carcinoma is a rare type of thyroid cancer that starts in the thyroid gland, an organ in the neck responsible for regulating metabolism. This cancer arises from special cells called parafollicular C cells, which produce a hormone called calcitonin. The disease can affect how the body controls calcium levels and may cause symptoms like a lump in the neck or difficulty swallowing. It can sometimes be inherited, meaning it runs in families due to changes in specific genes. Early detection is important because this cancer can spread to lymph nodes and other parts of the body. Treatment often involves surgery and monitoring hormone levels to track the disease.
Clinical Definition
Medullary thyroid carcinoma (MTC) is a malignant tumor originating from the parafollicular C cells of the thyroid gland, which secrete calcitonin. It accounts for approximately 3-5% of all thyroid cancers and can occur sporadically or as part of hereditary syndromes such as multiple endocrine neoplasia type 2 (MEN2) caused by mutations in the RET proto-oncogene. The tumor is characterized by amyloid stroma derived from calcitonin deposits and often presents with elevated serum calcitonin levels. Clinically, MTC may cause a neck mass, diarrhea, or flushing due to hormone secretion. It is significant because it tends to metastasize early to regional lymph nodes and distant sites, requiring prompt diagnosis and management. Genetic testing for RET mutations is critical for familial cases and guides screening of at-risk relatives.