“Poorly differentiated” refers to cancer cells that have more abnormalities and look less like normal cancer cells. Poorly differentiated thyroid cancer is uncommon, accounting for fewer than 5% of thyroid cancers. Poorly differentiated thyroid cancer is more clinically aggressive and can be challenging to treat. The cancer commonly spreads (metastasizes) to the neck lymph nodes, lungs, and bones. Poorly differentiated and well-differentiated thyroid cancers can be present at the same time.

Medullary and Hurthle thyroid cancers are considered poorly differentiated cancers.

Hurthle Cell Thyroid Cancer

Hurthle cell thyroid cancer (also called Hurtle cell carcinoma) is a rare type of thyroid cancer. Approximately 3% of thyroid cancer cases are Hurthle cell. Hurthle thyroid cells can be benign (noncancerous) or cancerous. Benign Hurthle cells usually do not recur once they are removed.

Hurthle cells are larger than follicular cells and have a pink-staining quality. Hurthle cell thyroid cancer tends to affect older adults and has a slightly poorer prognosis than follicular and papillary types. It spreads to the lymph nodes about 20% of the time.

Signs and Symptoms of Hurthle cell thyroid cancer

Hurthle cell thyroid cancer does usually not cause symptoms. Some patients with large nodules or advanced Hurtle cell thyroid cancer may notice:

  • Difficulty swallowing
  • Hoarseness
  • Shortness of breath when laying down
  • Pain (rare)

Diagnosis of Hurtle Cell Thyroid Cancer

Hurtle cell thyroid cancer cannot be diagnosed by fine needle aspiration biopsy (FNAB). The only way to diagnose cancerous Hurthle cells is by surgically removing the whole tumor.

The following tests may be ordered:

Blood tests

Blood tests help show if your thyroid is functioning normally. Tests commonly ordered check levels of thyroid-stimulating hormone (TSH) and T3 and T4 hormones. Blood tests are also used to monitor thyroid cancers.

Imaging tests

Advanced imaging scans of your neck help your physician see the precise location and extent of the suspected cancer including: Ultrasound scan (does not involve radiation), Computed tomography (CT) and scan Magnetic resonance imaging (MRI).

Medullary Thyroid Cancer

Medullary thyroid cancer accounts for around 5% of all thyroid cancer cases and is categorized into two types: sporadic (not inherited) and inherited. The sporadic medullary thyroid cancer accounts for around 80% of all medullary thyroid cancer cases. Genetic (inherited) medullary thyroid accounts for about 20% of cases and is caused by a mutation in the RET gene.

There are essential differences between medullary thyroid cancer and the papillary and follicular types. Medullary thyroid cancer stems from the C-cells of the thyroid, which make a hormone called calcitonin. Unlike thyroid hormone, calcitonin hormone has a minimal effect on metabolism.

Medullary thyroid cancer has a lower cure rate than papillary and follicular thyroid cancers. When the cancer is confined to the thyroid, the 10-year survival rate is around 90%. When it has spread to the lymph nodes, the 10-year survival rate is 70%. Patients with cancer found in distant structures have a 20% 10-year survival rate.

Signs and Symptoms of Medullary Thyroid Cancer

Medullary thyroid cancer often does not cause symptoms or signs. Some patients with large nodules and/or advanced medullary thyroid cancer may experience the same symptoms as other thyroid cancers and also include diarrhea (in some advanced cases).

Diagnosis of Medullary Thyroid Cancer

Blood tests

The blood calcitonin level is used in the diagnosis of medullary thyroid cancer.

Genetic testing

Patients with a family history of multiple endocrine neoplasia (MEN) syndrome or medullary thyroid cancer should be tested for genetic causes.

Biopsy

Fine-needle aspiration biopsy (FNAB) is the most effective test for determining if a thyroid mass is cancerous or not, and it has a 97% accuracy rate. This simple outpatient procedure involves a small needle injected into the mass or nodule. The needle removes cells that will be examined in the lab under a microscope.

Imaging tests

Advanced imaging scans of your neck help your physician see the precise location and extent of the suspected cancer including: Ultrasound scan (does not involve radiation), Computed tomography (CT) and scan Magnetic resonance imaging (MRI).