Follicular Carcinoma of Thyroid

Answer: c



Follicular carcinoma accounts for about 10% of all new carcinomas of the thyroid. Most patients are those with minimal invasion of the capsule or vessels within the neoplasms. Such tumors are seldom diagnosed definitively by either needle aspiration cytology or by frozen-section diagnosis at the time of lobectomy. Most frequently, the diagnosis is made after the study of permanent sections. Microinvasive encapsulated follicular carcinomas are rarely associated with metastatic lymph nodes and distant metastases involving bone are also rare at the time of diagnosis.

Angioinvasive follicular carcinomas are usually large and frequently show venous invasion of perithyroidal and lateral neck veins at the time of diagnosis. They may have already metastasized to different sites, most frequently the bone. These tumors are often diagnosed at the time of operation because of these characteristics. Most patients younger than 40 do well, but patients older than 50 years have a guarded prognosis. Follicular carcinomas of the thyroid are treated by total thyroidectomy. Lymphatic dissections are not usually required because only about 5% of all patients have lymphatic involvement. The most effective therapy for bone or pulmonary metastases is radioactive iodine. The controversy in the surgical management of follicular carcinoma is whether patients with low-grade encapsulated neoplasms diagnosed after total lobectomy by permanent section evaluation should be treated with total thyroidectomy. In patients with smaller follicular neoplasms found malignant as determined by microinvasion of the capsule, completion thyroidectomy is usually not done; instead patients are observed closely after performing a 99mTc bone scan to rule out occult bone metastases. Patients with large or high-grade angioinvasive lesions require total thyroidectomy.

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