The traditional approach for surgery of the thyroid gland is through the open technique. There has been a recent movement in some centers toward minimally invasive procedures, which include the minimally invasive video-assisted thyroidectomy innovated by the Italian surgeons and transaxillary robotic procedures made popular by the Korean group. I limit my remarks to the open technique.

Thyroidectomy is performed for structural and functional problems of the thyroid. The structural issues that require surgical consideration are tumors or other masses that compress adjacent organs (larynx, trachea, esophagus), tumors that are or are thought to be malignant, or large unsightly tumors. The vast majority of functional problems requiring thyroidectomy are hyperthyroid states.

Thyroidectomy has been performed in one form or another since the 12th century. Up until the late 19th century, it had been looked upon as a “dangerous” operation not to be taken lightly with the mortality being exceedingly high. Then, on to the surgical scene came Theodor Kocher, who was Chair of Surgery at the University of Bern, Switzerland. He refined the technique, bringing operative morbidity and mortality to an acceptable level; he was able to teach his methods to a host of surgeons from around the world, including William Halstead and Charles Mayo. Kocher won the Nobel Prize for thyroid surgery and left a legacy of technical skill so that surgeons around the world can now perform this procedure with safety and efficiency.

A brief discussion of the pathology of thyroid neoplasms is provided below in a separate section. In general, the broad classification of thyroid neoplasms includes benign tumors, well-differentiated malignant tumors, poorly differentiated malignant tumors, and medullary thyroid cancer. The incidence of thyroid cancer is increasing at a staggering rate—according to the American Cancer Society, the incidence has almost quadrupled in the last 20 years. However, the mortality rate has remained constant—this suggests that the true incidence is probably not rising but our detection rate, usually of tiny lesions, is. This increase in incidence is probably due to the increased use of ultrasonography of the neck, which is highly sensitive and detects masses in the thyroid that would not have been discovered by clinical examination, and if malignant, these masses may have never become clinically significant. In addition, there is an increased awareness by pathologists of the fine nuances of pathologic diagnosis of cancer of the thyroid, and perhaps the criteria applied recently would not have been in the past.

It must be borne in mind that a large segment of the population harbors asymptomatic microscopic cancer of the thyroid. Reports vary in autopsy and surgical studies; the highest incidence of cancer of the thyroid found in autopsies is in the Japanese and Finnish population (>30%). This fact should be considered when making decisions regarding management of microscopic disease detected by ultrasonography.

Several organizations such as the American Thyroid Association, National Comprehensive Cancer Network, and the British Thyroid Association have gone to great lengths to establish guidelines for the management of thyroid masses.

Benign masses in the thyroid gland can be disorders of colloid metabolism (i.e., colloid nodules), inflammatory conditions (i.e., various forms of thyroiditis such as Hashimoto’s), and benign neoplasms such as
follicular adenoma. Malignant tumors of follicular cell origin are either well or poorly differentiated. Tumors of parafollicular or C cells are medullary cancers of the thyroid.

The most common, well-differentiated thyroid malignancy is papillary carcinoma of the thyroid (PTC). There are now well-documented criteria for making the diagnosis. There are morphologic criteria, which consist of the identification of papillary formation, but it is necessary to detect nuclear and cytoplasmic criteria as well. The latter includes washed out nuclei (Orphan Annie nuclei), nuclear grooves, nuclear inclusions, micronucleoli, powdery chromatin, cellular overlapping and crowding, psammoma bodies, and atypical cells.

There exists a spectrum of pathologic appearances of PTC, which correlates with biologic aggressiveness of the cancer and ultimately outcome—these next three variants are the poorly differentiated types. Next in aggressive activity to the common PTC described above is the tall cell variant in which >50% of the lesion is comprised of cells where the height to width ratio is >3:1. Prognosis is poorer in this cancer than the more common PTC. Further along the spectrum is insular carcinoma in which the malignant-appearing cells tend to form little distinct islands or “insulae.” This is a particularly aggressive cancer. The final type of the PTC group is anaplastic carcinoma, which may demonstrate all of the characteristics of lesions mentioned above but has a highly malignant appearance with many bizarre cells, mitoses, and invasive behavior. This is one of the most aggressive cancers in the body, and the outcome is universally fatal. PTC is characterized by a significant propensity for regional metastatic spread to the central compartment lymph nodes and less frequently to the lateral neck.

The second common well-differentiated malignancy is follicular carcinoma. This cancer is characterized by vascular and/or capsular invasion. It should be noted that often the cells appear benign, but the aforementioned criteria qualify this tumor as malignant. Follicular carcinoma can metastasize to distant sites, most commonly to the lungs, by hematogenous routes. Results of treatment of this cancer are generally somewhat worse than the more common PTC. The third type of follicular-derived malignancy is the Hurthle cell carcinoma. This is a cancer comprised predominantly of “Hurthle cells” (also known as Ashkenazy cells or oncocytes) and is thought to be a variant of follicular cells. These cells are cuboidal and contain granular, eosinophilic cytoplasm. They are rich in mitochondria. These cancers may also demonstrate, as with follicular carcinoma, vascular and/or capsular invasion.

Medullary carcinoma of the thyroid, in contrast to the follicular cell-derived cancers, originates from parafollicular or C cells, which embryologically are neural crest derivatives. The cancer is comprised of spindleshaped cells in varying degrees of organization. One of the hallmarks of this cancer is the presence of amyloid detected by Congo red staining. This cancer can occur in a hereditary fashion, sporadically or with multiple endocrine neoplasia (MEN) syndromes. This cancer displays varying tendencies to aggressive behavior but has a marked propensity for lymph node metastases. The cancer secretes calcitonin and carcinoembryonic antigen so that immunohistochemical staining of these substances can make the diagnosis pathologically. Diagnosis and surveillance are also aided by serum determinations of both of these markers. Detection can also be made of the hereditary types in many cases by the determination of ret oncogene in the blood—this oncogene allows identification of suspected cases via umbilical cord blood in the newborn and in suspected family members in known kindreds facilitating early management of potentially lethal cases. The pathology in patients with hyperthyroid states demonstrate hyperplastic and convoluted papillae with a background of an inflammatory picture consistent with an autoimmune condition.

Most tumors are palpable and often visible when the patient presents with a mass that has been detected clinically. In patients whose tumors have been discovered by imaging, the mass is usually not palpable. Careful documentation of the characteristics of the mass should be performed as clues that may help facilitate diagnosis and surgical approach may be established (e.g., retrosternal goiter focuses attention to an approach to the mediastinum and a fixed hard mass may suggest malignancy). Those patients who present with lymph node metastasis present with palpable adenopathy in the lateral neck compartment(s).

Examination of the larynx is mandatory in any patient with a mass in the thyroid. The presence of impairment of vocal cord mobility in the presence of a mass in the thyroid is a strong predictor of an invasive malignancy.

Patients with hyperthyroidism should have a thorough system review for the documentation of signs of metabolic abnormalities.