Diagnosis and Management of Thyroid Nodules

Like all other organs of the body, the thyroid gland can develop lumps or nodules. Although thyroid nodules are very common, only a small proportion, probably less than five percent, contain cancer.

Of this small number of nodules that do contain cancer, nine out of ten are curable when proper treatment is given. Therefore, if you or your doctor discover a nodule (lump) in your thyroid gland, don’t panic.

To help yourself the most, follow your doctor’s recommendation for evaluation. In this way you and your physician will be able to find out whether your nodule is one of the 95 percent that are benign (harmless) or one of the 5 percent that are malignant (contain cancer). Since thyroid nodules are so common, an examination of your thyroid gland should be part of your annual physical examination. When the doctor feels the thyroid gland, it is called palpation. If you are a woman and your regular examinations are done by a gynecologist, ask your gynecologist to examine your neck and thyroid gland at the time of your checkup.

You may be the one to notice a lump in your thyroid gland, a gradual enlargement in the front of your neck, or perhaps trouble swallowing due to a thyroid growth. If so, call your physician and arrange to have an examination.

Examination and Blood Tests

During the evaluation of a thyroid nodule, your physician will try to determine whether the lump is the only problem with your thyroid or whether the entire thyroid gland has been affected by a more general condition such as thyroid inflammation (thyroiditis) or thyroid dysfunction (hyper- or hypothyroidism). Your physician will feel the thyroid to see whether the entire gland is enlarged, whether there is a single nodule present, or whether there are many lumps or nodules in your thyroid. A change in texture of your thyroid gland from soft and smooth to firm and irregular may suggest the presence of thyroiditis. Inflammation of your thyroid may lead to nodule formation from scarring or swelling, when there is no tumor.

During this same examination your doctor will try to determine whether you have any symptoms or signs to suggest that your thyroid is overactive or underactive. Either condition may be associated with thyroid nodules.

Blood tests will likely be ordered to determine whether your thyroid is producing too much, too little, or a normal amount of thyroid hormone. If your problem is a single thyroid nodule, normal results are usually obtained because most thyroid nodules do not produce thyroid hormone and the rest of the thyroid works as usual. Those few nodules that actively produce thyroid hormone without regard to the body’s need are called autonomous nodules. If you have one of these nodules, you may become hyperthyroid if your blood level of thyroid hormone rises above normal. Such nodules almost never contain cancer.

On the other hand, your physician may find that your thyroid blood levels are below normal, a condition known as hypothyroidism. Sometimes nodules develop in such underactive thyroid glands. A very common condition in which this occurs is chronic thyroiditis, also called Hashimoto’s thyroiditis in honor of the Japanese physician who first described it in 1912. If that is your condition, antibodies which develop against your thyroid cells can usually be detected by blood tests. Although a nodule in a patient with Hashimoto’s thyroiditis is probably part of the thyroid inflammatory process, thyroid cancers are sometimes seen in these patients. Therefore, further study of such a nodule may be necessary.

A blood test may also be helpful in a very uncommon form of thyroid malignancy known as medullary cancer, which produces a substance called calcitonin. Blood tests can detect calcitonin, sometimes even before a nodule can be felt. Medullary thyroid cancer sometimes runs in families. If the family history is positive, calcitonin blood tests can make the diagnosis early when the disease is very likely to be curable. However, since this disorder is uncommon, serum calcitonin is checked routinely only when there is a family history of this type of thyroid cancer.

Thyroid Imaging

Thyroid imaging is sometimes used as part of the evaluation of a thyroid nodule. The two imaging techniques are ultrasound and scintiscanning. Whether either of these types of thyroid imaging is used depends on the size of the nodule, the examination findings for the rest of the thyroid gland, blood test results, and the physician’s judgement. The purpose of the imaging studies is to help decide whether a needle biopsy test is needed, and, if so, to aid in directing the biopsy needles to the most appropriate spot. Imaging is not always necessary.

Needle Biopsy

A biopsy of a thyroid nodule may sound frightening, but the needle used is very small and a local anesthetic can be used. Therefore, you probably will not have much pain during the biopsy. More likely, you will experience a sensation of pressure or mild discomfort.

For a fine needle biopsy, your physician will use a very thin needle to withdraw cells from your thyroid gland. Ordinarily, several samples will be taken from different parts of your nodules to give your physician the best chance of finding cancerous cells if a tumor is present. These samples are processed like a Pap test and studied by the pathologist under a microscope.

It will usually be a few days before your physician receives the final report from the pathologist. The report will usually indicate one of the following findings:

1. The nodule is benign (not cancer). This is the result obtained in 50-60 percent of patients in whom enough tissue has been obtained in the biopsy test. This diagnosis by an experienced pathologist is highly reliable. The risk of overlooking a cancer is generally under three percent and even less when the biopsy is reviewed by an experienced pathologist at a major medical center. Generally, these nodules need not be removed. If a nodule subsequently enlarges, the biopsy can be repeated or the nodule removed by a surgical operation. Even when enlargement of such a nodule does occur, it is more likely to be caused by bleeding or degeneration inside the nodule, or by inflammation than by malignancy.

2. The nodule is malignant (cancer). If your needle biopsy produced a specimen of tissue or cells that is adequate for a careful pathological examination, there is about a 10 percent chance that a cancer is present. The pathology report may say that you have a definite cancer or describe findings that are “highly suspicious of malignancy.” All such nodules should be removed, and the presence of a cancer is nearly always confirmed at surgery. If you have such a malignancy, the extent of your operation will depend on the type of cancer, the extent of disease determined by tests before the operation, and also the findings during surgery. Your physician will want to choose an experienced surgeon to perform such an operation.

3. The specimen is inadequate to make any diagnosis. Accurate diagnoses cannot be made unless the sampling of tissue within the nodule obtained by biopsy has been adequate. About 10-20 percent of the time, physicians find that the tissues obtained from a thyroid biopsy are not adequate to reveal the nature of a nodule. Some thyroid nodules are composed of dense scar tissue or have undergone such extensive degeneration that recognizable thyroid tissue is not obtained by a biopsy. In this situation it is usually best to repeat the biopsy.

Some nodules may be too small or too deep in the neck to permit needle biopsy. If an adequate specimen cannot be obtained or if another needle biopsy is impractical, the decision to operate or just observe a thyroid nodule may be based on the physician’s experience in evaluating nodules, the physical examination, and the tests described above. Sometimes it is possible to get more adequate specimens if the needle biopsy is repeated using ultrasound guidance for directing the needle. This procedure requires experience and special ultrasound equipment.

4. The biopsy specimen contains enough thyroid cells, but the microscopic findings permit neither the diagnosis nor exclusion of thyroid cancer. About 15 percent of the time, needle biopsy of a thyroid nodule produces adequate numbers of thyroid cells, yet the pathologist examining the sample is still unable to tell whether a cancer is present or not. The only way to establish a definitive diagnosis on these nodules is to remove them surgically and carefully study them microscopically, looking for signs of malignancy. Here again, the results obtained at surgery will depend on the skill of the pathologist who examines the biopsy tissue, but most of such nodules (about 90 percent) prove to be benign. The decision about whether to have surgery in this situation depends on the size and other characteristics of the nodule and other aspects of the patient’s health.

In Summary

Diagnosis and management of thyroid nodules require skill and experience on the part of the physicians who participate in the evaluation. Needle biopsy can greatly improve the accuracy of diagnosis, significantly reduce the number of patients with nodules for whom surgery is advised, and at the same time identify and allow prompt treatment of a number of cancers that otherwise might be overlooked.

Above all, if you think you have a thyroid nodule, have it examined by your physician. Most nodules are benign and cared for easily. Even those that do prove to contain cancer are unlikely to develop into a life-threatening problem, since most thyroid cancers are curable. However, prompt diagnosis and treatment are advisable.