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Thyroidectomy
Removal of the thyroid gland

Thyroid surgery is performed

To treat thyroid cancer
  • To determine whether a nodule (lump) in the thyroid gland is benign (non cancerous) or malignant (cancerous). Thyroid nodules are very common, 90% of them are benign
  • To relieve pressure symptoms or blocking of the trachea (windpipe) related to nodular goiter (lumpy enlargement of the thyroid gland)
  • Infrequently to control hyperthyroidism (overactive thyroid)
  • Anatomy and Physiology

    The thyroid gland is an H shaped or butterfly shaped gland located in the lower neck in front of the trachea and between the carotid arteries (arteries to the brain). (Figures 1A,B and 2)

    Figure 1a - Front view of the thyroid gland showing the position of the gland in the neck and the position of the incision for thyroidectomy. © C. ScaliciFigure 1b - Front view of the thyroid gland showing the relationship of the gland to the trachea and larynx. © C. Scalici
    Figure 2 - Side view of the thyroid gland, parathyroid glands, larynx, trachea and esophagus. Also note the muscles at the back of the pharynx (throat). © C. Scalici

    • It has two lobes (rounded tissue parts) connected by an isthmus (bridge of tissue) with a rich blood
    • Parathyroid glands, which are brownish-yellow bodies of endocrine tissue, are located behind the thyroid gland
    • The nerves that supply the voice box (recurrent laryngeal nerve) run behind the thyroid gland in the groove between the trachea and esophagus (tube between the mouth and stomach
    • Being an endocrine gland, the thyroid gland does not have any ducts to carry away the thyroid hormone. The hormone enters the blood stream directly
    • The thyroid gland produces and stores the iodine containing thyroid hormone, which helps to regulate:
      1. Body metabolism
      2. Heart rate
      3. Blood pressure
      4. Temperature
      5. Growth and development
      6. Menstrual periods
      7. Muscle and nerve activity

    Pathology

    • Thyroid cancer is a disease where the thyroid cells become abnormal and grow in an unregulated manner forming a cancerous tumor, which has the potential to spread elsewhere
    • Thyroid cancer is the most common endocrine (hormone related) cancer. It accounts for about 1% of all cancers
    • National Cancer Institute (NCI) statistics show that thyroid cancer occurs in 2.5 males per 100,000 males and 6.7 females per 100,000 females
    • It affects all ages with increasing risk after 50 years of age
    • About 16,100 people are diagnosed with thyroid cancer per year
    • Overall, thyroid cancer survival rates are good at around 94%
    • There are four major types of thyroid cancer:
      1. Papillary carcinoma develops in cells that produce thyroid hormone. It is usually well differentiated (looks like normal thyroid cells and grows slowly), but tends to be multifocal in nature, that is, occurs in more than one site in the gland. Papillary carcinoma accounts for about 80% of thyroid cancer. It tends to spread locally (nearby) into lymph nodes and adjacent structures
      2. Follicular carcinoma develops in cells that produce thyroid hormone and is usually well differentiated. It has a10% chance of being multifocal and is more difficult to control because it tends to spread through the blood stream and grow into adjacent structures. It tends to take up radioactive iodine. This cancer makes up10% of thyroid cancers
      3. Hurthle Cell carcinoma is composed of "modified follicular cells". It is very similar to follicular carcinoma with a 25% chance of being multifocal. Unlike follicular carcinoma it does not tend to take up radioactive iodine. The tumor makes up 3.6 % of thyroid cancer and has a prognosis (patient outlook) similar to that of follicular carcinoma
      4. Medullary carcinoma arises from the parafollicular C cells of the thyroid gland that produce Calcitonin, a hormone that contains no iodine. It is more difficult to control because it metastasizes (spreads) to distant body sites. There are two types
      • Genetic disposition – this can be passed on in families and represents about 0.5% of thyroid cancers
      • Sporatic medullary - no genetic disposition but rather occurs randomly and represents 2.7% of thyroid cancers
    • Anaplastic carcinoma is poorly differentiated (does not look like normal tissue), aggressive and rapidly growing. It spreads rapidly into nearby structures. It represents 1.7 % of thyroid tumors
    • Others rare tumors that may develop in the thyroid are
      1. Lymphoma - composed of lymph cells
      2. Sarcoma - composed of cancerous connective tissue (tissue between functioning thyroid cells)
      3. Carcinosarcoma - composed of both malignant thyroid cells and connective tissue
    • Important microscopic features of thyroid tumors are:
      1. Differentiation level (what individual cells look like)
      • Well differentiated – the cells appear to resemble normal looking thyroid cells
      • Moderately differentiated – the cells are not normal but recognizable as thyroid cells
      • Undifferentiated – the cells are unrecognizable or barely recognizable as thyroid cells
      1. Capsular or vascular invasion - the tumor cells spread into the capsule (covering) of the thyroid gland or into the blood vessels. Invasion is needed to diagnose cancer in Follicular or Hurthle cell tumors because they are usually well differentiated
      1. Regional lymph node involvement – cancer is indicated when the neighboring lymph nodes contain tumor cells
      2. There is evidence of spread of tumor cells into adjacent structures (extracapsular invasion)
    • Type of tumor, age, tumor differentiation, capsular or vascular invasion, size of tumor, lymph node involvement and invasion of structures outside the thyroid determine prognosis. Age is a major criterion for prognosis with females under 45 years and males under 40 years having a very good outlook
    • Stage Information. Staging of thyroid tumors is important to assist in treatment decisions. The American Joint Committee on Cancer (AJCC) has designated staging by TNM classification as defined here
    Primary Tumor
    TX Primary tumor cannot be assessed
    T0 No evidence of primary tumor
    T1 Tumor is 1 cm or less in greatest dimension and limited to the thyroid gland
    T2 Tumor more than 1 cm but not more than 4 cm in greatest dimension and limited to the thyroid gland
    T3 Tumor more than 4 cm in greatest dimension and limited to the thyroid gland
    T4Tumor of any size extending beyond the thyroid capsule
    Regional lymph nodes (N) - The regional lymph nodes are the nodes in the cervical (neck) and upper mediastinal (space between the lungs) lymph nodes
    NX The regional lymph nodes cannot be assessed
    N0 No tumor in the regional lymph nodes
    N1

    Regional lymph node metastasis (invaded by tumor)

    N1a:Metastasis in ipsilateral (same side) cervical lymph node(s)
    N1b:Metastasis in bilateral (both sides), midline, or contralateral (opposite side) cervical or mediastinal lymph node(s)
    Distant metastases (M)
    MX Distant metastasis cannot be assessed
    M0 No distant metastasis
    M1 Distant metastasis
    • AJCC stage groupings
    Papillary or follicular thyroid tumor
    Under 45 Years
    Stage I Any T, Any N, M0
    Stage II Any T, Any N, M1
     
    Medullary thyroid tumor
    45 Years and older
    Stage I T1, N0, M0
    Stage II T2, N0, M0
     T3, N0, M0
    Stage IIIT4, N0, M0
     Any T, N1, M0
    Stage IVAny T, Any N, M1
    Anaplastic (undifferentiated) All cases are stage IV
    Stage I T1, N0, M0
    Stage II T2, N0, M0
     T3, N0, M0
     T4, N0, M0
    Stage IIIAny T, N1, M0
    Stage IVAny T, Any N, M1
      

    History and Physical Examination· A complete physical examination is performed

    • A complete physical examination is performed
    • Thyroid nodules are usually discovered by self-examination or by a physician on a routine neck examination. A family member or friend may remark that one side of the neck seems larger than the other
    • It is unusual to have neck symptoms such as difficulty in swallowing or difficult breathing
    • A history of previous x-ray or radiation to the neck is important. The cause of thyroid cancer is unknown but people with previous exposure to X-ray or radiation have a much higher incidence of thyroid cancer (usually papillary type)
      1. The radioactive fallout from the Chernobyl Nuclear Reactor has already led to a marked increase in thyroid carcinoma
      2. It is not unusual for the tumor to appear 20 years later
    • Many thyroid nodules today are being picked up by imaging studies that are being done for other reasons (ultrasound of the neck, CAT scan studies of the head, neck and chest)
    • Examination of the head and neck is important. Thyroid gland is assessed as to tumor size; firmness of the mass and whether single or multiple nodules are present
    • Swallowing will help in determining if the tumor is fixed to adjacent neck structures
    • Particular attention is paid to the entire neck for the presence of enlarged lymph nodes. The areas above the collar bones are evaluated for large lymph nodes
    • Listening to the chest while the patient breathes is important to detect any localized abnormal sounds that could be compatible with spread of the tumor to the chest

    Diagnostic Tests

    There are many tests for evaluating the thyroid gland and not all of them are required to determine whether surgery is indicated. They can be broadly broken into functional, anatomical, and cellular.

    • Functional - These determine how the thyroid gland functions and are performed on blood samples
      1. Thyroid hormone levels - this determines if the function of the thyroid is normal, underactive or overactive. This is not helpful in determining the presence of cancer
      2. Thyroglobulin - this is a protein that is produced in response to malignant cells and is usually elevated with cancer. It can also be followed postoperatively to see if any tumor recurrence has occurred
    • Anatomical
      1. Ultrasound - sound waves are passed over the neck structures and the bounced back waves are fed through a computer to image neck structures. Thyroid masses that are solid or cystic (contains fluid), enlargement of the thyroid, associated neck masses and blood vessels can be imaged
      2. Radioactive nuclear medicine studies - radioactive material is injected into a vein or swallowed by mouth and the thyroid gland takes up this material
      • Normal functioning thyroid will have a uniform uptake of the radioactive material
      • Hyperfunctioning tissue will take up more material and have a darker image (hot nodule) – this tissue is rarely malignant (Figure 3)
      • Hypofunctioning tissue will take up less of the isotope and have a lighter image (cold nodule) - 15 to 20% of these tissues are malignant
      • This study can also be used as a functional study - the amount of whole gland uptake can be determined to assess adequacy of thyroid function
      1. CAT scan - a computerized x-ray study that shows the detail of structures. The information obtained is similar to ultrasound but much more detailed
      2. Chest x-ray - will assess the lungs for presence of metastatic disease
      Figure 3 - Radioactive nuclear medicine study showing a 'hot' thyroid nodule in a patient with hyperthyroidism. Courtesy J. Bender, MD
    • Cellular
      1. Fine Needle Aspiration (FNA) - a very small needle is introduced into the nodule and cells are aspirated (sucked out) for study. This may be done by holding the nodule in the fingers or under ultrasound guidance. The specimen is sent to the pathologist for evaluation. The results are usually read as:
      • Nondiagnostic - which means the specimen was inadequate for evaluation and should be repeated to be meaningful
      • Indeterminate - not certain as to whether the specimen is malignant but suspicious changes are noted. This is usually considered to be an adequate specimen and a repeat FNA not suggested since surgery will usually resolve the status
      • Malignant – The cells showing malignant features
      1. Core biopsy - a small solid cylinder of the thyroid nodule is removed with a larger needle, which gives ample tissue to make a diagnosis. This is not usually done because of a higher complication rate compared to FNA
      2. FNA or Core biopsies may also be performed on neck masses not in the thyroid gland

    Indications and Contraindication for Surgery

    • Indications:
      1. Cancer demonstrated by examination of the cells or by biopsy of tissue
      2. Needle biopsy shows some suspicious cells
      3. Large nodular thyroid with compression especially of the airway
      4. Hyperfunctioning nodule causing hyperthyroidism (Figure 3)
      5. Multiple Endocrine Neoplasia syndrome - inherited endocrine syndrome involving adrenals, thyroid, parathyroids and occasionally non endocrine soft tissue tumors - where Medullary carcinoma of the thyroid is frequent
      6. Hyperthyroidism (Graves' disease) that cannot be controlled with anti- thyroid medications or radioactive treatment
      • Hyperthyroidism rarely requires surgery today. It will typically be treated with anti thyroid drugs (slow down thyroid function) or radioactive medications (knock out thyroid cell function permanently)
      • In the past, women in the childbearing age were not considered good candidates because of possible gene altering effects. This thinking has waned more recently and more treatment has been carried out with radioactive medication
      • If the patient has a single hyperfunctioning nodule that cannot be controlled with medication, surgery may be indicated. Contraindications to antithyroid drugs or radioactive substances would possibly require surgery
    • Contraindications:
      1. Medical conditions exist that would make survival from a general anesthetic and operation unlikely
      2. When life expectancy is limited due to other conditions

    Surgery

    • There are essentially four types of thyroid operations:
      1. Lobectomy and isthmusectomy - one lobe and the isthmus connecting the two lobes are removed. A thyroid nodule alone is not usually biopsied or enucleated but rather an entire lobe is removed (Figure 4)
      1. Bilateral subtotal thyroidectomy - a small remnant of thyroid tissue is left in place on the backside of the thyroid to provide protection for the parathyroid glands and recurrent laryngeal nerves. The isthmus is also removed (Figure 5)
      Figure 4 - Thyroid lobectomy - removal of one lobe and isthmus of the thyroid. © C. ScaliciFigure 5 - Bilateral subtotal thyroidectomy - near total removal of both lobes leaving small remnants of the thyroid gland and the parathyroid glands. © C. Scalici
      1. Near total thyroidectomy - all of the gland except a small portion on the opposite side is removed - this would be left to protect the parathyroid glands and recurrent laryngeal nerves (Figure 6)
      1. Total thyroidectomy - the entire thyroid gland is removed leaving the parathyroid glands. (Figure 7)
      Figure 6 - Near total thyroidectomy - complete removal of one lobe of the thyroid with almost complete removal of the other lobe. The parathyroid glands are preserved. © C. ScaliciFigure 7 - Total thyroidectomy - total removal of all thyroid tissue with preservation of the parathyroid glands. © C. Scalici
    • The type of thyroid operation is determined by the age of the patient, cell type of tumor, size of the tumor, presence of capsular or extracapsular (outside the capsule) tumor and invasion of adjacent structures
    • Most papillary tumors will be treated with near total or total thyroidectomy because they tend to be multicentric (start in several places in the gland) in origin. Tumor will develop again in 5 to 10% of cases if appreciable thyroid tissue is left behind
    • Most follicular tumors are treated with near total or total thyroidectomy. Follicular tumors have a lesser incidence of multicentricity but they spread via the blood stream. They tend to have a 5 to 10% recurrence if appreciable thyroid tissue is left behind. They can, however, be treated with radioactive iodine if they recur but any tissue left behind has to be removed.
    • Total thyroidectomy is the treatment of choice for medullary carcinoma
    • Anaplastic tumors cannot be removed and a tracheostomy (tube placed in the trachea for breathing) is frequently performed to avoid airway obstruction.
      1. At the time of surgery, any enlarged or suspicious lymph nodes are removed
      2. Depending upon the situation this lymph node removal might be extended to a modified neck dissection of one or both sides of the neck
      3. A modified neck dissection involves removing the lymph nodes around the carotid artery and internal jugular vein
      4. Any structures involved with direct tumor extension are removed except for the trachea
      5. The recurrent laryngeal nerve to the vocal cords may have to be sacrificed on the side of the gland involved with tumor
    • Surgery is performed under general anesthesia with the patient lying on her back with the neck arched back by placing a roll under the shoulders
      1. A lower neck curved incision is made.
      2. The skin, subcutaneous (under the skin) tissue and platysma muscle, which lies just under the skin) of the upper portion of the incision are mobilized (dissected and moved) to the upper edge of the Adam's apple. The lower end is mobilized to the sternum (breastbone).
      3. A midline incision is made through the cervical fascia (fibrous tissue layer) in order to mobilize the neck muscles on either side of the thyroid gland to each side.
      4. The gland is inspected carefully along with an examination of the neck structures for the presence of any enlarged lymph nodes. The type of malignancy and the amount of the gland involved will determine the extent of the operation. Any of the four types of operation described above may be performed
      5. The blood vessels of the gland are clamped, cut and ligated (tied off). The gland is carefully mobilized to preserve the parathyroid glands and the recurrent laryngeal nerves. The extent of the operation will determine the number of blood vessels to be ligated and divided
      6. Additional lymph nodes may be removed or a modified neck dissection performed.
      7. The pathologist immediately examines the surgical specimen
      • The pathologist may be able to give a definite diagnosis then or additional studies may be needed to make a definite diagnosis of the thyroid tissue.
      • It is extremely difficult for the pathologist to make a definite diagnosis where follicular adenomas (noncancerous) and follicular carcinomas (cancers) are concerned.
      • The same problems arise for Hurthle cell adenomas and Hurthle cell carcinomas. It is necessary to see invasion of the capsule or vessels to make the diagnosis of malignancy for follicular and Hurthle cell carcinomas. This almost always requires overnight preparation of the specimen with special treatment of the tissue to be examined under the microscope
    • Surgery provides the best results for thyroid cancers

    Additional Treatment

    • The final staging of the tumor will determine the extent of any additional treatment. This treatment will consist of:
      1. Giving thyroid hormone to replace that produced by the removed gland- this tends to suppress differentiated tumors
      2. Radioactive iodine to ablate (kill) any residual thyroid tissue following operation and can be effective in treating recurrence
      3. External beam radiation to the neck - eliminates local residual disease
      4. Radiation during surgery is being investigated
      5. Chemotherapy - drugs that kill tumor cells are given
      6. Clinical trials - patients can enroll in studies in which treatment results are not known
    • Recurrent disease is treated by surgery and or a combination of the above

    Complications

    • Complications are usually directly related to the severity of the disease. The larger more aggressive tumors require more extensive and difficult operations and, therefore, a higher rate of complications. Complications consist of:
    • Bleeding
    • Hypoparathyroidism - causes low serum calcium if the blood supply to the parathyroid glands are compromised or these glands are removed with the surgical specimen
      1. A typical thyroidectomy has an incidence of 1-3%
      2. A difficult extensive thyroid cancer removal rate is between 5-10%
      3. There may be transient hypoparathyroidism which resolves with time
    • Recurrent laryngeal nerve paralysis - there may be transient or permanent paralysis of the vocal cords due to nerve injury. If both nerves are compromised, the patient will have airway obstruction and will need a tracheotomy. The usual thyroid operation has an incidence of around 1%. One functioning nerve will usually provide good speech and adequate airway
    • Infection
    • Airway compromise - this is rare except for anaplastic carcinoma
    • Pneumonia may occur but is unusual after thyroid surgery
    • Thrombophlebitis (blood clots in the veins) of the legs is unusual after thyroid surgery

    Postoperative Care

    • The patient is usually kept in the hospital overnight
    • Intravenous fluids are given overnight
    • Regular vital signs checks (blood pressure, heart rate, respiratory rate, temperature, urine output) are taken
    • Careful observation of the neck to see if any unusual swelling occurs
    • The patient is asked about tingling symptoms of the fingers or face that may be a symptom of low blood calcium. The nurse or doctor may tap the side of the face over the facial nerve to see if the nerve is irritable another indicator of low blood calcium
    • Serum Calcium levels may or may not be drawn
    • The patient usually has a sore throat which does not last very long
    • The patient should be able to be out of bed later in the day and have a liquid to soft diet the evening of surgery
    • The patient may experience some nausea (sick to the stomach)
    • Pain medication is provided as needed
    • Most people desire to go home the next day

    Care After Discharge

    • The patient should walk, eat and drink after discharge
    • The incision should be kept clean and one may shower over the incision
    • May drive in 2-3 days and possible to return to work in 5-7 days
    • The surgeon usually sees the patient in 5-10 days
    • Thyroid functional status will need to be determined. This is done through blood tests. Thyroid hormone is frequently necessary and is done soon after surgery
    • The patient may need to delay taking thyroid hormone for several weeks so a radioactive nuclear medicine uptake study can be performed to see if any residual thyroid gland is present if there was a malignancy. If residual thyroid gland is present, the patient may be given radioactive iodine to ablate (knock out) any residual tissue
    • The type of thyroid cancer and the staging of the cancer will determine additional treatment such as radioactive iodine, chemotherapy and radiation therapy
    • Repeat clinical exams, laboratory blood studies, chest x-rays, nuclear medicine scans, possible CAT scans of the neck and chest may be carried out if there was a malignancy
    • If the diagnosis is cancer of the thyroid, it is necessary to have long term follow-up - if you move you should establish follow at your new residence. The patient's physician can help establish follow up and provide important medical records