Thyroid Medullary Carcinoma

Overview
  • Thyroid Medullary Carcinoma is a type of malignant neoplasm of the thyroid gland derived from the thyroid parafollicular cell, also known as C Cells. The vast majority of cases are due to sporadic appearance although familial cases can occur as part of MEN 2.
Morphology
  • Gross Appearance
    • Thyroid Medullary Carcinomas usually present with solitary or multiple nodules of the neck although multiple nodules are more common in familial cases
  • Histological Appearance
    • Neoplastic cells can form multiple architectures and can be invasive. Characteristically, surrounding tissue is laden with a proteinacious amyloid-like deposit which represents collections of tumor-secreted calcitonin, the peptide hormone normally secreted by parafollicular cells.
Clinical Consequences
  • Thyroid Medullary Carcinoma usually presents as nodularity of the neck. Although tumors are functional and thus produce large amounts of calcitonin, blood calcium levels are typically not affected. In some cases, tumors produce other peptide hormones such as VIP which can present as unexplained secretory diarrhea. Tumors are malignant and can undergo metastasis although sporadic cases usually have a good prognosis. Sadly however, familial cases associated with MEN 2 can be highly aggressive.