Thyroid for Dummies (17 page)

The reason that so much attention is paid to the lumps on your thyroid is the same reason why a piece of property is valuable: location, location, location.

If the thyroid gland grew inside your chest or abdomen, all these little growths would never get noticed and would cause few problems. Instead, your thyroid is positioned right up front, where everyone can see and feel it, and provides a lifetime source of work for thyroid specialists – some of whom like to call themselves
thyroidologists
. Most specialists call themselves
endocrinologists
, however, as they also have their work cut out dealing with other mis-firing endocrine glands. (An endocrine gland is one that secretes hormones directly into the blood stream rather than into a duct.) This chapter tells you all you need to know about thyroid lumps and bumps by explaining which types of nodules cause concern and which to safely ignore, as well as what happens if you need to have your lump removed. Most thyroid 12_031727 ch07.qxp 9/6/06 10:46 PM Page 82

82
Part II: Treating Thyroid Problems

nodules are minor inconveniences and knowing what to do about them tends to keep them that way.

Discovering a Thyroid Nodule

Kenneth is a 35-year-old man in excellent health. While shaving one day, he notices a bump on the front of his neck that he has not seen before. He ignores it for several months but finally decides that he ought to ask someone to check it out. He goes to his doctor, who does thyroid function tests. His free T4 and thyroid-stimulating hormone (TSH) levels are normal (refer to Chapter 4). His doctor then sends him to a thyroidologist for evaluation.

The thyroidologist asks Kenneth if the lump has grown noticeably and if it causes any trouble when swallowing or breathing. Kenneth answers ‘no’ to these questions. The specialist then proposes that Kenneth has a
fine needle
aspiration biopsy (FNAB)
(check out Chapter 4). When this test is done, the hospital report identifies the lump as a
benign thyroid adenoma
, which means it’s not cancerous. Kenneth is told to come back in a year for a re-examination.

A year later, the test shows no change, and the specialist asks him to return a year after that. Kenneth forgets about coming back for re-testing and the consultant’s secretary fails to remind him – even so, Kenneth lives happily ever after.

Kenneth’s a very good example of the typical case history of a person with a thyroid nodule. He illustrates the unexpected finding of a lump, the tendency to ignore it, and the fact that it generally isn’t a problem in the long run.

This case is not meant to detract from the fact that some nodules are diagnosed as cancer and are dealt with promptly. This example simply illustrates the most common course of events.

The thyroid is ordinarily a smooth butterfly-shaped gland (refer to Chapter 3).

Whenever something grows that alters that smoothness, the growth is called a
nodule

A person may have one or several growths on their thyroid, and multiple explanations for why they appear. Physicians identify the various possibilities according to the appearance of the nodule tissue under a microscope.

This process is known as the pathological appearance of the tissue. For most purposes, doctors and patients alike just want to know whether the nodule is benign (not cancerous) or malignant (cancerous).

The good news is that most thyroid nodules – 90 per cent or more – are benign.

12_031727 ch07.qxp 9/6/06 10:46 PM Page 83

Chapter 7: Getting the Low-Down on Thyroid Nodules
83

Evaluating Cancer Risks

A number of facts about a person’s thyroid history, signs, and symptoms can help to sway the balance towards or away from a diagnosis of cancer: ߜ If a person has many nodules, this suggests that a cancer is not present.

Most multinodular thyroids are benign.

ߜ A most important point in a person’s history is previous exposure to radiation. (This exposure doesn’t include the use of radioactive iodine in the treatment of hyperthyroidism – go to Chapter 6.) For example, children exposed to radiation from the Chernobyl Nuclear Plant in Russia show a significant increase in thyroid cancer. In this case, multiple nodules do not rule out cancer as almost half the nodules in an irradiated gland are cancerous.

ߜ A nodule that grows rapidly is probably a cancer, but if it pops up suddenly and is tender, this suggests a haemorrhage. A haemorrhage of this form is not usually a serious problem, but it does cause discomfort.

ߜ Nodules are found less often in men than women, but are cancerous more often in men, when they are found.

ߜ Nodules found in children are cancerous more frequently than they are in adults. However, a nodule in a child is still benign more often than it is malignant.

ߜ Virtually no family or hereditary connection is associated with nodules, either benign or cancerous. The exception is a condition called
multiple
endocrine neoplasia
where many members of a family have nodules on several different glands, such as the thyroid, the pancreas, the parathyroids, and the adrenal glands.

ߜ Symptoms of hoarseness and trouble with swallowing suggest cancer.

ߜ Finding growths in the neck away from the thyroid suggests cancer that has spread, and those growths are also evaluated by a biopsy.

ߜ If the thyroid doesn’t move freely, it’s a sign of fixation that suggests cancer.

Securing a Diagnosis

When a GP sees someone with a thyroid lump, the practitioner asks about associated symptoms, such as difficulty breathing or hoarseness, and examines the neck to check for enlarged lymph nodes. If any of these signs or 12_031727 ch07.qxp 9/6/06 10:46 PM Page 84

84
Part II: Treating Thyroid Problems

symptoms are present, the doctor then picks up the phone and arranges immediate referral to a thyroid specialist clinic. Although most people would like ‘immediate’ to mean the same day, in clinical practice it is usually accept-able for immediate to mean within two weeks. If no other symptoms or signs are present, the doctor takes blood to check the thyroid function and autoantibody status. If this test is normal then the person is also referred as soon as possible to a thyroid specialist clinic so that a nodule that is cancerous is rapidly differentiated from one that is benign. If the thyroid function tests are abnormal, then the person is routinely referred to an endocrinologist. Thyroid function tests that suggest hyperthyroidism (refer to Chapter 6) or hypothyroidism (Chapter 5 covers this condition) usually mean that a thyroid nodule is benign. However, two different conditions can exist within the thyroid at the same time. Therefore, doctors examine a coexisting nodule occasionally to ensure that it’s not growing.

Once you reach the thyroid specialist clinic, the team arrange tests to correctly diagnose the nature of the nodule.

The fine needle aspiration cytology

This test is the gold standard for diagnosing a single thyroid nodule. Usually, specialists skip the other tests and go right to this simple, painless, and very specific procedure. A tiny needle is stuck into the nodule, sometimes under the guidance of ultrasound, and cells are removed using suction. A cell pathologist with a special interest in thyroid disease then examines the cells under a microscope (hence the word
cytology
, which means study of cells) to find out whether they are cancerous or benign. When sucking out the cells and any fluid, the doctor notes whether or not the nodule resolves – that is, disappears. If the nodule is a fluid-filled cyst that doesn’t fully disappear after aspiration, the remaining lump is aspirated again, and the specimens examined separately. Doctors believe that this test gives the correct diagnosis 94

per cent of the time, with false positive or false negative results occurring in only 6 per cent of cases. To ensure accuracy, a cytology specimen from a non-cystic nodule is only accepted as adequate if it contains six or more groups of at least 10 thyroid follicular cells. If the sample is rejected as not adequate, the fine needle aspiration is repeated to obtain more cells. In this situation, ultrasound guidance allows more accurate targeting of the nodule, which is often quite small. Where results suggest the nodule is from a nodular goitre or due to thyroiditis, a further fine needle aspiration cytology is carried out after three to six months to exclude cancer.

12_031727 ch07.qxp 9/6/06 10:46 PM Page 85

Chapter 7: Getting the Low-Down on Thyroid Nodules
85

The thyroid ultrasound scan

A
thyroid ultrasound scan
(check out Chapter 4) gives a picture of the entire thyroid and demonstrates if more than one nodule is present. More helpful than that, an ultrasound can distinguish between a solid mass and a cyst. A cyst is a nodule that is filled with fluid or contains some solid tissue. A cyst filled with fluid is usually a benign growth. A cyst that contains some solid tissue is sometimes a cancer. The scan can detect cystic nodules as small as 2mm wide and solid lumps that are only 3mm wide.

A
radioactive iodine uptake and thyroid scan
(refer to Chapter 4) is often not necessary when diagnosing a thyroid nodule. Sometimes, the test is useful to distinguish a nodule that takes up radioactive iodine from one that does not.

A nodule can actively concentrate iodine even though the thyroid function tests are normal. A ‘warm’ nodule takes up radioactive iodine like the rest of the gland. If the nodule concentrates most of the iodine (while the rest of the gland is less active) and the thyroid function tests are elevated, it’s a ‘hot’

nodule. Cancerous nodules are usually ‘cold’, meaning they do not concentrate the radioactivity. However, most cold nodules are not cancerous.

Figure 7-1 shows the typical appearance of a cold nodule and a hot nodule.

Figure 7-1:

A hot nodule

and a cold

nodule.

Hot nodule

Cold nodule

In addition, the thyroid scan sometimes shows multiple nodules when only one was seen or felt. Multiple nodules argue against a cancer.

12_031727 ch07.qxp 9/6/06 10:46 PM Page 86

86
Part II: Treating Thyroid Problems

Treating Cancerous Nodules

Every so often, one of these anonymous nodules is diagnosed as a cancer (see Chapter 8), and treatment is necessary. (Sometimes, the tests available to a doctor do not provide a definitive diagnosis, in which case the best step is to treat the nodule as if it is cancerous, just in case.) The treatment of choice for a cancerous thyroid nodule is surgery. Even benign nodules are sometimes removed surgically if they are unsightly or cause compression or trouble with swallowing.

When surgery is necessary, there are two key requirements: ߜ A competent surgeon with plenty of experience in thyroid surgery is vital as potential complications can arise when operating in this part of the neck (see Chapter 13). A general surgeon who carries out only occasional thyroid cases does not usually undertake thyroid surgery for possible cancer, as the cancer is sometimes extensive. Furthermore, the procedure needs to be done successfully the first time around, as a second surgery is much more difficult and complicated due to the formation of scar tissue. For this reason, doctors refer suspected thyroid cancers to a specialist surgeon or endocrinologist who is a member of the local Regional Thyroid Cancer Multidisciplinary Team.

ߜ An experienced pathologist is also vital to diagnose the type of tissue that the surgeon removes, as surgery proceeds. The pathologist’s opinion determines whether the surgeon just removes the lump, or carries out a complete removal of the thyroid (called a
total thyroidectomy
) and removal of lymph nodes in the neck to see if the cancer has spread. This extensive operation is only carried out if the pathologist can give the surgeon a precise diagnosis. Ideally, the final diagnosis of the tissue, made after surgery is complete, doesn’t contradict the diagnosis made during the operation.

Dealing with Nodules That

Are Non-Cancerous

Hot nodules and benign cysts may require some treatment, but not necessarily surgery. Dealing with the thyroid non-surgically is always preferable because of the potential for surgical complications . Every person has the right to discuss their treatment with their doctor and to request removal of the nodule if they prefer, however. For those who wish to avoid surgery, other treatment choices are available for nodules that are not cancerous.

12_031727 ch07.qxp 9/6/06 10:46 PM Page 87

Chapter 7: Getting the Low-Down on Thyroid Nodules
87

Hot nodules

A hot nodule produces hyperthyroidism so it needs treatment. One choice is to give the person radioactive iodine (RAI), as is done for Graves’ disease (refer to Chapter 6). However, up to 40 per cent of people treated with RAI develop hypothyroidism (underactive thyroid) later in life. Those who do not develop hypothyroidism usually return to normal thyroid function.

A newer treatment that eliminates the hot nodule while not destroying the rest of the thyroid gland is the injection of ethanol (alcohol) into the nodule.