“Hypoechoic” is a medical term that refers to the growth of tissue in the body that is denser than usual. Hypoechoic Thyroid Nodules are solid growths within the thyroid gland that are only detected during a high-resolution ultrasound imaging test. The risk of malignancy with Hypoechoic Thyroid Nodules is on the higher side because thyroid nodules in general, are liquid filled lumps while Hypoechoic Thyroid Nodules are solid nodules.

However, a complete diagnosis including tests such as an FNA biopsy (Fine Needle Aspiration) from a healthcare provider could only confirm this. Most thyroid nodules are benign growth (non-cancerous), but knowing more about thyroid nodules, malignant nodules can provide a patient with significant knowledge on management and treatment options for the same.

This article provides a structured overview of hypoechoic thyroid nodules, including their characteristics, diagnostic approaches, treatment options and the role of Interventional radiology to treat thyroid nodules.

What is a Hypoechoic Thyroid Nodule?

Hypoechoic Thyroid Nodules are Thyroid lesions that appear to be darker than surrounding tissue on high resolution ultrasound imaging diagnosis. These nodules can be solid and can contain cystic component which calls for the need to get it evaluated immediately as it can pose risk of thyroid malignancy. A thyroid nodule biopsy is also done to determine if the thyroid nodule is benign or if it possesses malignant features.

Characteristics of Hypoechoic Nodules

Thyroid Gland

Firstly, the thyroid gland is a butterfly shaped, ductless endocrine gland located in the front portion of the neck. Notably it is also one of the largest endocrine glands weighing on an average of 25-30 grams. The thyroid gland is responsible for producing the thyroid hormone, which controls your body’s metabolism.

Thyroid Cancer

Thyroid nodules grow within the thyroid gland and are mostly benign nodule. However, in some cases thyroid nodules need to be further evaluated to confirm if they are benign thyroid nodules or malignant thyroid nodules.

Thyroid cancer is a type of cancer due to malignant nodule growth and have the potential to spread to other parts of the body. Thyroid Cancer can have various effects on the body and can cause symptoms such as voice change, difficulty swallowing or can even lead to nodal metastasis which basically means cancer that can spread to the lymph nodes. Here are the characteristics of Hypoechoic thyroid nodule that one needs to keep a note of,

Risk of Thyroid Cancer

One needs to keep in mind that generally hypoechoic thyroid nodule is benign. But, hypoechoic thyroid nodules can be associated with a higher risk of thyroid cancer. Conclusions can only be drawn after accurate diagnosis which involves physical examination of the patient, ultrasound imaging, biopsy. A fine needle aspiration biopsy (FNA Biopsy) or a thyroid nodule biopsy is the most effective method to find out if a thyroid nodule is cancerous or otherwise.

Size does play a Role

The size of the thyroid nodules does matter. Larger thyroid nodules are more prone to mischievous as they can affect thyroid function. A 3mm Hypoechoic thyroid nodule may need a different follow up than a 6mm Hypoechoic nodule.

Symptoms and Signs of Thyroid Nodules

Often, people with thyroid nodules show no symptoms. This is the reason why it is usually detected during imaging diagnosis. There are a few symptoms that might give you a hint such as, difficulty breathing, swallowing. A bigger thyroid nodule can lead to voice change or even hoarseness. Some of the other symptoms are,

• Lump in the Neck
• Throat Hoarseness
• Voice Change
• Trouble Swallowing
• Difficulty Breathing
• Constant Cough

Are Hypoechoic Thyroid Nodules Cancerous?

As mentioned, most thyroid nodules are benign, however the probability of a Hypoechoic thyroid nodule turning out to be cancerous is higher. Since a Hypoechoic thyroid nodule is a solid nodule, it appears to look dark on an ultrasound scan whereas normal thyroid nodules are fluid filled lumps.

This does not mean that a benign thyroid nodule must not be treated if it causes notable symptoms. In the case of thyroid malignancy, one type of thyroid cancer is medullary thyroid cancer. Medullary thyroid cancer is cancer which forms inside the thyroid gland known as the medulla.

What is the most common type of Thyroid Cancer?

Papillary Thyroid Cancer/ Papillary Thyroid Carcinoma

Studies reveal that, over the past ten years the incidence of Thyroid Cancer in India is on the rise. Papillary Thyroid Cancer (PTC) is the most common type amongst thyroid cancers. Papillary Carcinomas form in the follicular cells of the thyroid gland and produce protein called thyroglobulin. There are various subtypes of Papillary Thyroid Carcinomas one of which is known as mixed papillary follicular variant.

How is Thyroid Nodules Diagnosed?

Ultrasound Evaluation

Ultrasound is the go-to imaging method for evaluating thyroid nodules. It provides accurate diagnosis of thyroid with detailed images and is completely non-invasive in nature. Ultrasound features such as coarse calcifications, tall than wide, increased flow of blood and irregular edges can be helpful to detect thyroid malignancy.

In certain cases, were thyroid nodules show risk of malignancy additional diagnostic methods are preferred to confirm the type of thyroid disease. In case of nonpalpable thyroid nodules which are smaller than 1cm in diameter, an ultrasonography is recommended. Here are a few suspicious features to watch out for on an ultrasound evaluation.

Irregular Margins

The edges of a thyroid nodule reveal key information on its nature. Thyroid malignancies are often detected in an ultrasound evaluation when they show irregular margins. The edges of benign nodules are smooth and well defined. On the other hand, malignant nodules often have irregular, blurry margins.

Hypo Echogenicity

One of the most important aspects of potentially malignant thyroid nodules is hypo echogenicity. According to ultrasound features, hypo echogenicity refers to how much sound wave reflection happens from a structure in the body. A hypoechoic thyroid nodule reflects fewer sound waves and appears to be darker than surrounding tissue.

Grow Tall rather than Wide

Another notable ultrasound feature that detects malignant nodules is the way they grow. Benign thyroid nodules grow horizontally, while a malignant nodule tends to grow vertically. This acts as an indicator for presence of cancer cells and can be easily noticed during an ultrasound.

Fine Needle Aspiration Biopsy

If the healthcare providers tend to find suspicious features in the ultrasound or doubt risk of malignancy, they ask the patient to undergo biopsy. According to American Thyroid Association Guidelines, thyroid nodules with highly suspicious ultrasound features are eligible for a biopsy. In a FNA biopsy, a thin needle and a syringe is utilized to pull out cells, tissues and fluids from the thyroid nodules. Then the healthcare provider sends the sample to a cytology lab to get them tested.

Blood Tests

Blood tests are also prescribed by the healthcare providers to monitor thyroid function and check for abnormalities. TSH, T4, T3, Thyroid Antibodies, Thyroglobulin and Calcitonin are few blood tests that needs checked before drawing conclusions.

Treatment Options for Thyroid Nodules

Depending on the type of growth of thyroid nodules, treatment options differ. If the thyroid nodules turn out to be malignant treatment options such as a surgery is preferred. If the thyroid nodules are benign, minimally invasive approaches such as Radiofrequency Ablation can also be opted, preserving surrounding tissue and is usually a day care procedure.

Observation

Benign nodules may be recommended to be watched over before immediate requirement for intervention. This will only be suggested if the thyroid function is also observed at regular intervals. If the thyroid nodule turns out to depict thyroid cancer, then thyroid surgery such as thyroidectomy which involves the removal of some, or all of the thyroid gland is preferred.

Surgical Treatments Thyroid Cancer

Thyroid Cancer poses increased risk and thereby surgeries such as thyroidectomy or lobectomy is suggested to prevent the cancer from spreading to other parts of the body. Here are a few surgical options to treat Thyroid Cancer.

Thyroidectomy

Thyroidectomy is a surgical procedure that involves removing a part of the thyroid gland or the entire thyroid gland in itself. Thyroidectomy can also treat thyroid nodules in certain cases, depending on the severity. Thyroidectomy is considered a major surgery and is often preferred to treat thyroid cancer as it helps eliminate the risk of any type of reoccurrence.

The only huge disadvantage is that if the thyroid gland is completely removed, production of the thyroid hormone is disrupted. This can cause symptoms such as weight gain, hormone imbalance and even fatigue.

Radioactive Iodine Treatment

Radioactive Iodine Treatment also known as RAI is a therapy that is used to treat certain typed of thyroid cancer. This radioactive treatment targets cancer cells specifically to eliminate them permanently. This procedure is completely safe and is preferred as a wise solution to treat specific types of thyroid cancers.

Interventional Radiology

Radiofrequency Ablation (RFA)

Radiofrequency Ablation is an Interventional Radiology technique that uses radio waves to create a current that heats a small portion of the nerve tissues. An interventional radiologist uses ultrasound features to precisely detect the area of tumor. They then insert a probe through the skin into the thyroid nodule to send these radio waves which heat up the cancer cells in the nodule, causing them to die.

Alcohol Ablation

Alcohol Ablation is a non-surgical treatment that uses concentrated ethanol alcohol solution to cut off the blood supply to cancer cells in the neck lymph nodes causing them to die. This treatment can be used to shrink large thyroid cysts and also destroy reoccurring thyroid cancer without a surgery.

Conclusion

Hypoechoic Thyroid Nodules range from benign to potentially malignant conditions. Understanding their characteristics and management strategies is crucial. Interventional radiology offers innovative treatments like RFA, providing effective options with less recovery time than traditional surgery. Regular follow-ups with healthcare providers remain essential for optimal outcomes.