Hürthle cell adenoma is a rare form of thyroid cancer that disproportionately affects women. Like all adenomas, Hürthle cell adenomas are benign, but they have the potential to become carcinomas, which are malignant.
Hürthle cell adenoma was first identified by Dr. James Ewing in 1928 (the cells themselves were discovered by Karl Hürthle in 1894), and most cases occur in patients between seventy and eighty years old.
Even large clusters of Hürthle cells may not be life threatening, but Hürthle cell adenomas have the potential to become malignant and metastasize to other bodily organs.
Symptoms and Risk Factors
Hürthle cell adenomas and carcinomas have a higher incidence in people who have other, non-malignant thyroid problems like Graves disease, colloid nodular disease, lymphocytic thyroiditis, thyroid hyperplasia, parathyroid adenoma, and follicular adenomas.
Patients who have experienced excessive irradiation of the head and neck are also at increased risk, especially for malignancy.
The most common clinical sign of a Hürthle cell adenoma is a palpable mass in the thyroid, although this may only be noted by a doctor.
Patients may feel pain or pressure in the affected area, and those with malignant conditions (Hürthle cell carcinoma) may experience difficulty swallowing, shortness of breath, coughing, choking spells, or hoarseness. Some patients with Hürthle cell adenomas also suffer from hypothyroidism (under active thyroid gland).
Is the Hurthle Cell Tumor 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. Benign Hurthle cell tumors are not a threat at all and should not come back once they are removed.
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 age of patients with Hurthle cell cancer is 55 years old, about 10 years older than patients with follicular cancer.
Like follicular cancer, Hurthle cell thyroid cancer infrequently spreads to lymph nodes (about 10%), but it can recur locally (the cancer can come back in the neck) or spread to the lung or bone.2
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 that does not have extensive invasion, especially in a younger patient (under 45 years old), can have an excellent prognosis.
The first step in diagnosing a Hürthle cell adenoma is to establish the existence of a thyroid tumor. Second, a physician must determine whether the tumor is malignant or benign.
Preliminary data about the location and size of the tumor is usually gleaned through imaging technology such as CT scans, MRI scans, or ultrasounds. Tests of thyroid function are also helpful.
After a tumor is detected, the next step in attaining a proper diagnosis requires the extraction of tissues from the tumor to be examined in a laboratory under a microscope.
This tissue extraction may involve the minimally invasive fine needle aspiration biopsy technique, whereby a needle is inserted into the tumor to collect cancer cells for study.
Hurthle Cell Thyroid Cancer Treatments
Patients with Hurthle cell thyroid cancer, if there is more than minimal invasion, should generally undergo removal of all or nearly all of their thyroid tissue (see our article 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.
Surgery 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 a 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.
Hurthle Cell Thyroid Cancer Conclusion
It’s important to treat Hurthle cell carcinoma early. Fortunately, there are several treatment options for Hurthle cell thyroid cancer. Your doctor will walk through all of your treatment options with you.