Follicular Thyroid Cancer

Excerpt

The thyroid is an endocrine gland located just below the cricoid cartilage in the neck, and it is composed of both the right and the left lobes separated by an isthmus. The thyroid gland functions to produce the thyroid hormone, which is needed by the body to carry out different metabolism. Follicles comprise the thyroid and are the functional and structural units of the gland. Epithelial cells line the follicles, which could be cuboidal or columnar, depending on the state of activity. These cells could develop abnormal growth causing follicular malignancy. Thyroid cancer is one of the most common endocrine tumors and is classified as differentiated or undifferentiated. Differentiated cancers include papillary and follicular thyroid carcinoma, and undifferentiated types include medullary thyroid cancer and anaplastic cancer. Papillary thyroid cancer accounts for most varieties. Follicular thyroid cancer is the second most prevalent type, accounting for 10 to 15% of all thyroid cancer. The undifferentiated types are rare when compared to the differentiated types.

Up to half of follicular carcinoma cases show RAS point mutations, while one-third may show PAX-PPAR-gamma rearrangements, and only 3% show both. Follicular thyroid cancer is a tumor of the follicular cells that are cuboidal epithelial cells and have capsular and vascular invasive properties. Compared to follicular carcinoma, follicular adenoma is benign and occurs more commonly with a ratio estimated to be 5 to 1. This article will focus more on the follicular type of thyroid cancer, discussing the etiology, epidemiology, histology, evaluation, staging, and complications of follicular thyroid cancer.