Metastatic Medullary Thyroid Carcinoma
Medullary Thyroid Carcinoma (MTC) - Nodal Metastases: MTC accounts for 1-2% of thyroid cancers in the US. It arises from the neural crest-derived parafollicular C cells of the thyroid gland. MTC may occur sporadically or in a hereditary form (as a component of MEN2A or MEN2B as well as familial MTC). The RET protooncogene on chromosome 10q11 contains germline mutation in most of the hereditary/familial cases and somatic mutations in 50% of sporadic tumors. Almost 70% of patients with MTC who present with a thyroid mass have metastases to cervical lymph nodes. The frequency of involvement of various nodal groups is as follows: central compartment nodes level VI (50-75% of cases), followed by mid-jugular (level III) and lower jugular (level IV) nodes, and less commonly to high jugular (level IIA) and supraclavicular (level V) nodes. Upper mediastinal (level VII) nodes may show metastases if there is extensive involvement of level VI nodes. Some studies have found an association between preoperative serum calcitonin levels and the risk of nodal metastases. If the levels are below 20 pg/ml, there is virtually no risk of nodal metastases. Image copyright: pathorama.ch.