Hurthle Cell Thyroid Cancer- Not Quite the Same as Follicular Cancer

Hurthle cell cancer of the thyroid is usually classified with follicular thyroid cancer, although it really is a distinct kind of tumor. It is an unusual tumor, making up about 4% of thyroid cancers and is only about 1/4 as common as follicular cancers.

Benign or Malignant?

Like follicular tumors, there are benign Hurthle cell tumors and malignant Hurthle cell tumors, and the pathologist tells the difference between them based on invasion of the capsule and the blood vessels. Sometimes we have to wait for three or four days after the surgical procedure to remove the thyroid for the final pathology to be available to tell us whether there is any invasion. Benign Hurthle cell tumors are not a threat at all and should not come back once they are removed.

What is a Hurthle Cell?

A Hurthle cell is a kind of thyroid cell which has a distinctive look: under the microscope it is bigger than a follicular cell and has pink-staining cellular material.

How is Hurthle Cell Cancer Different from Follicular Cancer?

Hurthle cells look different than other types of thyroid cells and they tend to occur in older patients. The median (most common) age is patients with Hurthle cell cancer is 55, about 10 years older than patients with follicular cancer. Like follicular cancer, they infrequently spread to lymph nodes (about 10%) but can recur locally (the cancer can come back in the neck) or spread to lung or bone.  This usually takes years to become manifest. Because younger patients with thyroid cancer tend to have a better prognosis than older patients with a very similar tumor, and because Hurthle cell cancers occur in older patients, they have the reputation of being more dangerous. However, if you control for age and other factors like size and initial extent of tumor (whether it has spread locally in the neck or elsewhere in the body), Hurthle cell tumors behave very similarly to follicular tumors. A small Hurthle cell cancer which does not have extensive invasion, especially in a younger patient (under 45), can have an excellent prognosis.

How is Hurthle Cell Cancer Treated?

Patients with Hurthle cell cancer, if there is more than minimal invasion, should generally undergo removal of all or nearly all of their thyroid tissue (see our page on the different types of thyroid surgery). In all areas of well-differentiated thyroid cancer, there is some disagreement about how extensive the surgery should be; however, because Hurthle cell tumors tend to occur in patients with more serious risk factors, the surgery is correspondingly more aggressive. If there are involved lymph nodes they are removed although this is uncommon. This may be followed with radioactive iodine. Radioactive iodine does not work as well for Hurthle cell cancer as it does for follicular cancer, because the Hurthle cells are less likely to "take up" the radioactive iodine and then be destroyed by it. However, it is well-tolerated treatment and may be helpful in some cases. Patients are then followed at regular intervals to check for recurrence, which can be dangerous in Hurthle cell cancer and needs to be watched for carefully. Bottom line, Hurthle cell thyroid cancers are very curable if you have a good thyroid surgeon and a good endocrinologist.... The vast majority of people should be cured of this cancer.

 Dr Laura E. Sanders practices endocrine and general surgery at the Lahey Clinic Medical Center in Burlington, Mass.

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