Thyroid Disorders

Thyroid cancer is a malignancy arising from the thyroid gland cells: thyroid follicular cells (papillary, follicular, and anaplastic carcinomas) and calcitonin-producing C cells (medullary carcinomas). Rare cancers are derived from the lymphocytes (lymphoma) and/or stromal and vascular elements (sarcoma). Driver mutations involving the receptor tyrosine kinase pathway (such as RET and BRAF) and a family history of cancer or related syndromes increase the risk. Exposure to ionizing radiation and iodine deficiency are also considered risk factors. The major types can present as thyroid nodules or enlarged cervical lymph nodes. The diagnostic approach includes thyroid-stimulating hormone, ultrasonography, and biopsy. Treatment options are surgical removal of the thyroid gland, with the addition of radioactive iodine therapy and systemic therapy, depending on the type and extent of the thyroid malignancy.

A goiter is a chronic enlargement of the thyroid gland due to nonneoplastic growth occurring in the setting of hypothyroidism, hyperthyroidism, or euthyroidism. Morphologically, thyroid enlargement can be diffuse (smooth consistency) or nodular (uninodular or multinodular). Hashimoto’s thyroiditis is associated with a benign hypothyroid goiter, while Graves’ disease produces a toxic or hyperthyroid goiter. Nontoxic goiter is euthyroid and is usually due to iodine deficiency (the most common cause of goiter). Diagnostic tests include thyroid function tests and measurement of thyroid antibodies. Ultrasound, CT, and/or MRI help if lab results are ambiguous and if worrisome features such as obstructive symptoms are present. Radioactive iodine uptake distinguishes hyperthyroid causes. Treatment depends on the underlying condition; options include observation, medication, surgery, and radioiodine ablation.