Virtually all tumors of the thyroid gland arise from glandular cells and are, therefore, adenomas or carcinomas. Functioning adenomas were discussed previously (see the section “Toxic nodular goiter”).
On thyroid scan, 90%–95% of thyroid adenomas are cold nodules and come to attention only if they are large enough to be physically apparent. Diagnostic testing involves a combination of approaches, including ultrasonography (cysts are benign and simply aspirated), fine-needle aspiration, and surgery, depending on the clinical situation. Treatment options for benign cold nodules are suppressive therapy, in which thyroid hormone replacement is used to suppress TSH secretion and its stimulatory effect on functioning nodules, and surgery.
There are 4 types of carcinomas of the thyroid: papillary, follicular, medullary, and anaplastic (undifferentiated). Papillary carcinoma is the most common form of thyroid tumor. Tumors removed before extension outside the capsule of the gland appear to have no adverse effect on survival. Follicular carcinoma may also be associated with a normal life span if it is identified before it becomes invasive, but late metastases can occur. Medullary carcinoma arises from the C cells and produces calcitonin. The lesion can occur as a solitary malignant tumor or as part of multiple endocrine neoplasia type 2 (discussed at the end of the chapter). Anaplastic carcinoma, though rare, is the most malignant tumor of the thyroid gland and is found mainly in patients older than 60 years. For the giant cell form, the survival time is less than 6 months from time of diagnosis; for the small cell form, the 5-year survival rate is 20%–25%.
Ponto KA, Kanitz M, Olivo PD, Pitz S, Pfeiffer N, Kahaly GJ. Clinical relevance of thyroid-stimulating immunoglobulins in Graves’ ophthalmopathy. Ophthalmology. 2011;118(11): 2279–2285.
Excerpted from BCSC 2020-2021 series: Section 1 - Update on General Medicine. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.