Hurthle cell cancer is a very rare form of thyroid gland cancer. It is a differentiated type of cancer which means that it contains cells and tissues that look like the original thyroid cells and have a specific function. This also points to the fact that they grow and spread more slowly than cancer cells that are not well differentiated. However, this specific type of cancer only makes up less than 10% of all the known types of differentiated thyroid cancers leading to a very low number of research interest. The World Health Organisation (WHO) has put this cancer under follicular thyroid cancers and in a sub-class known as oxyphilic.
A view under the microscope will show these cancer cells to be large and usually have a polygonal shape, numerous granules in their cytoplasm, big nuclei and a big nucleolus which is centrally placed. They also have cell borders that are defined.
Hurthle cells were described for the first time in the 19th century by Askanasy. There is a scientific dispute on the origin of hurthle cells but the general consensus is that they are formed from follicular epithelium. They can be found in other tissues apart from the thyroid gland including the parathyroid gland, the liver, trachea, kidney, larynx, salivary glands and pituitary gland.
These cells can be either benign or malignant and we cannot differentiate which form it falls under by doing a Fine-needle aspiration biopsy. We have to take out a section of the lump and if possible a lymph node close to it to check for the shape, color spread to nearby tissues and lymph nodes. Hurthle cell cancer has the highest propensity to spread to other tissues among differentiated cancers of the thyroid gland. There are hopes that doctors can buy stem cells online for the treatment of this disease.
Signs And Symptoms
There are no specific symptoms for hurthle cell cancer. The symptoms are more of the general symptoms that point towards malignancy especially in the thyroid gland.
- Growth: Usually, this is the first thing that patients notice indicating there might be a problem. They might feel an abnormal bulging in their neck which might then become more noticeable as time goes on.
- Difficulty in swallowing
- Coughing incessantly
- Change of voice- the tumor may compress on the vocal cord or the recurrent laryngeal nerve causing hoarseness of voice.
- Pain – Some patients might start to feel pain as the growth gets bigger.
- Difficulty in breathing or shortness of breath
- Horner syndrome- this may occur if the sympathetic nerve ganglia are It is a triad of symptoms including drooping eyelids (ptosis), constriction in the pupils (miosis), apparently decreased sweating on the affected part of the face (anhidrosis)
- A positive family history of hormonal problems or/and cancer.
Causes
The specific cause is not known. However, there are many risk factors that have been implicated in the development of this type of thyroid cancer. They include:
- Exposure to radiation over a long period of time. This could be from multiple medical radiotherapies to the head and neck regions as a treatment for previous cancer, or a nuclear accident where radioactive substances are released into the atmosphere for a long time like the 1986 Chernobyl accident in
- Iodine deficiency for a long period of time has been implicated as a risk factor for developing follicular cancer.
Diagnosis
- Thyroid function tests- When a patient presents with a possible case of thyroid cancer, the first thing is to order blood tests to check the thyroid function. This includes checking for the Thyroid-stimulating hormone (TSH), Thyroxine (T4), Triiodothyronine (T3), Thyroglobulin and Anti-thyroglobulin antibodies, Antiperoxidase antibodies.
However, many patients with Hurthle cell disease actually have normal blood and thyroid function tests so other imaging studies need to be done regardless.
- Thyroid Ultrasound- An ultrasound can tell whether the mass is solid or fluid-filled (cystic), the size of the mass, the location and if the surrounding lymph nodes are enlarged.
- Thyroid uptake and scan- This can tell whether it is a hot nodule i.e functioning or if it’s a cold nodule i.e non-functioning. A hot nodule is usually benign while a cold nodule is usually malignant. In hurthle cell cancer, the scan would typically show a cold nodule.
- Fine-needle Aspiration – This is a biopsy where contents of the nodule are sucked into a needle and then analyzed by a cytologist. It is effective in diagnosing Hurthle cell neoplasm but it cannot determine if it is benign or malignant.
- MRI of the neck- This can show the relation of the growth to the surrounding structures in the neck
- CT scan or Positron Emission Tomography scan of the neck- This will give a detailed picture and can also show calcifications.
Staging
Staging Hurthle cell carcinoma takes a little turn from the routine staging system for cancers because it involves:
- Age- the age of the patient is taken into serious consideration and at present, the blanket age used for the classification is 45. Stage 3 and 4 of the cancer is always seen in patients above 45 years old.
- Size- if a tumor is less than or equal to 1cm, it’s classified as T1 and it would fall under stage 1. If greater than 1cm but less than 4cm, it’s classified as T2, if greater than 4cm, its classified as T3. T2 and T3 will fall into stage 2. If a tumor extends beyond the thyroid capsule, it’s classified as T4 and would fall into stage 3.
- Lymph node spread – Also known as “N” in the TNM classification system. If there is any lymph node involvement (i.e N1), the tumor falls under stage 3.
- Spread to distant structures- Also known as “M” in the TNM classification system. If there are any distant metastases (i.e M1), the tumor falls under stage 4 regardless of what the size or lymph node involvement is.
Treatment
The only optimal treatment for Hurthle cell carcinoma currently is Surgery. The type of surgery depends on the stage of cancer, whether it is benign or malignant, the patient’s wishes.However, it is important that ALL the Hurthle cells are removed from the thyroid gland. The various types of surgeries done are:
- Thyroid lobectomy- usually done initially to diagnose whether a tumour is benign or malignant.
- Total thyroidectomy- removal of the entire thyroid gland
- Extended thyroidectomy- done in stage 4 types when cancer has spread to other structures.
Stem Cell Therapy
Scientists are presently working on understanding how cancer stem cells contribute to relapse and resistance to treatments. This is important to creating an effective therapy for the treatment of Hurthle Cell Carcinoma
References
Haigh, P. and Urbach, D. (2005). The treatment and prognosis of Hürthle cell follicular thyroid carcinoma compared with its non-Hürthle cell counterpart. Surgery, 138(6), pp.1152-1158.
Krhin, B., Goricar, K., Gazic, B., Dolzan, V. and Besic, N. (2016). Functional polymorphisms in antioxidant genes in Hurthle cell thyroid neoplasm – an association of GPX1 polymorphism and recurrent Hurthle cell thyroid carcinoma. Radiology and Oncology, 50(3).
Ristevska, N., Stojanoski, S. and Pop Gjorceva, D. (2015). Appearance of Hürthle cell carcinoma soon after surgical extirpation of Hürthle cell adenoma and follicular adenoma of the thyroid gland. Radiology and Oncology, 49(1).
