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Hurthle cell cancer (HCC) is a rare form of cancer affecting the butterfly-shaped thyroid gland in the front part of the lower neck. Although the thyroid weighs less than an ounce, it secretes hormones that are essential to properly regulate your body's metabolism.

Among new cases of thyroid cancer, less than 5 percent are Hurthle cell cancers. The condition is also called Hurthle cell carcinoma and sometimes oxyphil cell carcinoma. Noncancerous (benign) Hurthle tumors are more common than cancerous forms of the disease.

Hurthle cell cancer can be aggressive, and surgery to remove the thyroid is the most common treatment. Most people with Hurthle cell cancer have a good prognosis and excellent long-term survival. However, if Hurthle cell cancer is diagnosed in its later stages, the outlook may be poorer than for other forms of thyroid cancer.

A number of signs and symptoms are associated with thyroid cancer — and specifically Hurthle cell cancer — although these characteristics may not be present in the earliest phases of the disease. These same signs and symptoms may also be indications of other medical conditions — such as an infection of the thyroid gland or a noncancerous enlargement of the thyroid (goiter).

The most common clinical sign of Hurthle cell cancer is a fast-growing lump (nodule) in the neck, just below the Adam's apple. Other signs and symptoms of Hurthle cell cancer may include:

• Enlarged and swollen lymph nodes in the neck
• Pain in the neck or throat, with pain sometimes extending to the ears
• Hoarseness or other changes in the voice
• Shortness of breath
• Trouble swallowing
• A continuous cough not associated with an upper respiratory infection

The precise cause of Hurthle cell cancer is not known, although researchers believe the disease is associated with alterations in DNA, including some related to the aging process. DNA is the genetic material that contains the instructions for every chemical process in your body. Some of the genes in your DNA promote cell division, and some slow cell division or program cells to die at the right time. Still other genes control processes that help repair DNA. When DNA is altered or damaged, these genes may not function properly, causing cells to grow out of control and eventually form a mass (tumor) of malignant cells.

Like other thyroid cancers, Hurthle cell cancer has been linked to radiation exposure, particularly during childhood, with the disease developing many years or even decades after exposure.

Doctors still have unanswered questions about Hurthle cell cancers, including how to classify them. HCC is often considered a subgroup of so-called follicular tumors of the thyroid, which develop in the thyroid's follicle cells. These are cells in which thyroid hormones — thyroxine and triiodothyronine — are manufactured. Some researchers, however, believe that HCC should be considered a distinct category of thyroid malignancies.

A number of factors may increase your risk of contracting Hurthle cell cancer. Some studies have suggested that male gender, older age and radiation treatments to the head and neck can raise the likelihood of developing HCC. Differences in risk among racial groups are also seen in thyroid cancer in general, with white people at greater risk than black people are.

If you have any signs or symptoms associated with Hurthle cell cancer, contact your doctor. An evaluation by your doctor and appropriate diagnostic tests can determine whether these signs or symptoms are caused by Hurthle cell cancer or another medical condition.

If your doctor suspects Hurthle cell cancer, the first steps will be to go over your medical history and conduct a physical exam. Your doctor will examine your neck, checking the size of your thyroid and seeing whether lymph nodes in the neck are swollen.

To help make a definite diagnosis, your doctor may recommend one or more of the following tests:

• Ultrasound scan. This painless imaging technique, also called a sonogram, uses high-frequency sound waves to outline the neck anatomy and detect a thyroid tumor. A doctor or person who is trained to perform ultrasound exams (sonographer) will place gel on your neck and then place a handheld transducer on the area. The transducer transmits sound waves into the neck region and sends information to a computer to create a series of pictures of the thyroid — including images of its shape and size. While very good at identifying whether a tumor is present, ultrasound scans can't tell for sure whether a growth or nodule is malignant or benign. Ultrasound is safe, with virtually no complications associated with its use.

• Fine-needle aspiration biopsy (FNA). This test may determine whether a tumor or nodule is cancerous or noncancerous. In this procedure, you lie down and the doctor passes a fine needle through the skin of your neck. Your doctor may use ultrasound imaging to help direct the needle into the tumor. As the needle is withdrawn, cellular material is taken out (aspirated). Then the process is repeated to obtain cells from several regions of the growth. These cell samples are placed on glass slides and sent to a laboratory for microscopic analysis by a pathologist to determine whether the nodule is cancerous. In many instances, the results of the biopsy are inconclusive, which could lead to a laboratory finding of "Hurthle cell neoplasm suspicious for cancer." In such cases, surgical removal of the nodule is necessary to confirm whether cancer is present. Most tumors turn out to be benign after the thyroid is surgically removed.

  Fine-needle aspiration can be performed in your doctor's office or at an ambulatory surgical center, and it usually takes 10 to 20 minutes. Because the needle is very thin (much thinner than a needle used to withdraw blood from the arm), it causes only slight discomfort. Your doctor may apply a local anesthetic to the area to eliminate any chance of pain. Some people experience a small amount of temporary bleeding, bruising or swelling at the site where the needle was inserted. People who are taking aspirin or blood thinners have a greater risk of bleeding. In rare cases, an infection may occur at the site.

You won't need to do much preparation for either of these tests. No fasting is required. In most cases, you won't need to stop taking any medications.

Other diagnostic tests such as magnetic resonance imaging (MRI) and positron emission tomography (PET) are used much less often.

Possible complications of all thyroid tumors, including Hurthle cell cancer, include difficulty swallowing and breathing if the tumor grows and presses on the esophagus.

If HCC isn't treated appropriately, or if treatment begins late, the cancer can spread (metastasize) to other tissues and organs, making therapy more difficult and diminishing the chances of recovery.

Several approaches are available to treat HCC:

• Surgery. Surgery is the best treatment for Hurthle cell cancer. During this operation all or nearly all of the thyroid is removed. The procedure is called a near total thyroidectomy. The surgeon leaves tiny edges of thyroid tissue near the adjacent parathyroid glands to lower the likelihood of parathyroid injury. These small parathyroid glands regulate your body's calcium level. Surrounding lymph nodes are removed to determine if the cancer has spread to them.

  Before the surgery, your doctor will conduct a complete physical exam, including a heart evaluation to determine the risk of cardiac complications during the operation. Blood tests can reveal if you have a bleeding disorder that could become problematic. You'll be asked to avoid eating and drinking, beginning the night before the operation.

  The greatest risk associated with the operation is unintended injury to the recurrent laryngeal nerve. Such injury could cause permanent damage to your voice, but this occurs rarely.

  You'll need to stay in the hospital for at least one night after the operation to ensure that post-surgical bleeding hasn't occurred and that you're able to breathe normally.

• Thyroid hormone medication. After surgery for Hurthle cell cancer, your doctor will prescribe the synthetic drug levothyroxine (Levoxyl, Synthroid, Levothroid), which replaces the hormones no longer being produced because of the absence of the thyroid. You'll need to take these synthetic hormones for the rest of your life. They're safe, with minimal risk of side effects.

• Radioactive iodine therapy. Radiation therapy using a capsule containing radioactive iodine 131 is often prescribed as an adjunct to surgery for Hurthle cell cancer. It can be used to destroy any microscopic thyroid tissue remaining after the operation, using a modest dose of radiation in a procedure called "remnant ablation." At times, a higher dose of radioiodine can be used to eliminate any malignant cells that have spread to other parts of the body, such as the lungs and bones.

  Radioactive iodine therapy is typically administered about six weeks after surgery, generally as an outpatient procedure. Higher doses of this treatment may require hospitalization for two or three days.

  In rare cases, radioiodine therapy can cause temporary side effects including sore throat, dry mouth, decrease in taste sensations, neck tenderness, nausea and vomiting. Patients who are already taking thyroid hormone medication must stop its use for about two weeks before radioactive iodine therapy starts. Nearly all traces of the radioactive iodine are excreted from the body within about two days after the capsule has been taken. Doctors avoid this form of treatment in pregnant and breastfeeding women because of risks to the fetus and newborn.

• External beam radiation. This approach delivers radiation treatment to attack malignant cells. It's sometimes an option for people in whom radioiodine therapy hasn't been successful. It uses a special X-ray machine called a linear accelerator to deliver radiation to cancer cells, typically five times a week over a period of six to eight weeks. This treatment can target specific areas where cancer cells are present, minimizing damage to nearby healthy tissue. Side effects may include a temporary reddening and sensitivity of the skin.

There are few specific measures you can take to prevent Hurthle cell cancer. However, you may be able to lower your risk by reducing your exposure to radiation from X-rays and other sources.

Although many alternative or nontraditional treatments — from vitamins to herbs — are sometimes promoted for use in patients with cancer, none has been proved helpful in the management of Hurthle cell cancer or other types of thyroid cancer. If you have questions about a specific alternative treatment, talk with your doctor.