fbpx

Follicular thyroid carcinoma

Updated : May 20, 2024





Background

Follicular thyroid cancer is a type of thyroid cancer that originates from the follicular cells of the thyroid gland. The thyroid gland in the front of the neck produces hormones that regulate metabolism. Thyroid cancers are relatively uncommon but are generally treatable. Follicular thyroid cancer arises from the follicular cells of the thyroid gland. These cells produce thyroid hormones, primarily thyroxine (T4) and triiodothyronine (T3).

Like many cancers, the exact cause of follicular thyroid cancer is often unknown. However, certain risk factors may increase the likelihood of developing thyroid cancer, including a family history of thyroid cancer, exposure to high levels of radiation, and certain genetic conditions. Follicular thyroid cancer is characterized by the formation of follicles or structures resembling follicles. The cancer cells may invade blood vessels and, in some cases, spread to distant organs, particularly the lungs and bones.

Epidemiology

Follicular thyroid carcinoma represents a smaller proportion of thyroid cancers compared to papillary thyroid carcinoma, but it is one of the more common types. The incidence varies geographically, with higher rates reported in certain regions, including some areas with iodine deficiency.

Follicular thyroid carcinoma can occur at any age, but it is more commonly diagnosed in adults. The incidence tends to increase with age. There is generally a higher incidence in women compared to men. The prevalence of certain risk factors, such as iodine deficiency, may contribute to regional differences in the incidence of follicular thyroid carcinoma.

Anatomy

Pathophysiology

Follicular thyroid carcinoma arises from the follicular cells of the thyroid gland, specifically the cells that line the thyroid follicles. Normal thyroid follicular cells produce thyroid hormones (T3 and T4) that play a crucial role in regulating metabolism. Genetic mutations are often implicated in the development of follicular thyroid carcinoma. Specific genetic alterations may drive the transformation of normal thyroid cells into cancerous cells.

Common mutations include alterations in genes such as the RAS and PAX8/PPARγ genes. Follicular thyroid carcinoma typically presents as a well-defined tumor within the thyroid gland. The tumor often forms follicles or structures resembling normal thyroid follicles, and these cancerous follicles may invade nearby tissues. In some cases, follicular thyroid carcinoma may invade blood vessels. This vascular invasion can facilitate the spread of cancer cells to other parts of the body, particularly the lungs and bones.

Metastasis is a critical aspect of the pathophysiology of cancer. Follicular thyroid carcinoma may metastasize to distant organs through the bloodstream. Distant metastases, especially to the lungs, are a characteristic feature of more advanced cases. Angiogenesis, the formation of new blood vessels, is often promoted by cancer cells to ensure a blood supply for the growing tumor. The development of new blood vessels facilitates the nourishment of cancer cells and supports their ability to invade and metastasize. Follicular thyroid carcinoma is often classified into stages based on the size of the tumor, extent of invasion, and presence of metastasis.

Etiology

Genetic Factors:

There is evidence that genetic factors play a role in the development of follicular thyroid carcinoma. Specific genetic mutations, such as mutations in the RAS gene and alterations involving the PAX8/PPARγ gene, have been associated with follicular thyroid carcinoma.

Iodine Deficiency:

Iodine is an essential element for the production of thyroid hormones. Chronic iodine deficiency has been linked to an increased risk of thyroid cancer, including follicular thyroid carcinoma. However, in some well-nourished populations, follicular thyroid carcinoma can still occur.

Radiation Exposure:

Exposure to ionizing radiation, especially during childhood, is a well-established risk factor for thyroid cancer. Individuals exposed to radiation from nuclear accidents, therapeutic radiation treatments, or certain occupational exposures may have an elevated risk of developing follicular thyroid carcinoma.

Age and Gender:

The risk of follicular thyroid carcinoma increases with age and is more common in adults. Women tend to be more commonly affected than men.

Genetics

Prognostic Factors

Clinical History

Follicular thyroid carcinoma often presents as a thyroid nodule. Palpation or imaging studies may reveal the presence of a lump in the thyroid gland. Swelling or enlargement of the thyroid gland, leading to changes in the appearance of the neck, may be observed. Compression of nearby structures by the tumor can lead to symptoms such as difficulty swallowing or hoarseness.

Follicular thyroid carcinoma may affect thyroid hormone production, leading to symptoms of hypothyroidism or hyperthyroidism. However, these symptoms are often subtle. While thyroid cancers, including follicular thyroid carcinoma, are often painless, some individuals may experience discomfort or pain in the neck area.

In advanced cases with metastasis, individuals may experience systemic symptoms such as unintentional weight loss, fatigue, or changes in appetite. The onset of symptoms can vary. In some cases, follicular thyroid carcinoma may be asymptomatic and discovered incidentally during a routine examination or imaging study. Some individuals may have persistent symptoms for an extended period, while others may notice more rapid changes.

Physical Examination

Palpation of the thyroid gland may reveal the presence of a nodule or mass. Follicular thyroid carcinoma often presents as a solitary thyroid nodule. The thyroid gland may be enlarged, leading to an increased size of the neck. This enlargement could be due to the presence of a tumor. Follicular thyroid carcinomas may have a firm or hard consistency compared to benign thyroid nodules.

However, it is important to note that physical examination alone cannot definitively distinguish between benign and malignant nodules. Thyroid nodules are typically non-tender. Tenderness may be associated with inflammation or other thyroid conditions but is less commonly observed in thyroid cancer. Large thyroid tumors may cause compression of the trachea, leading to tracheal deviation. This can result in respiratory symptoms such as difficulty breathing.

Compression of the recurrent laryngeal nerve by a thyroid tumor can lead to hoarseness or changes in voice quality. In some cases, thyroid cancers may be associated with eye symptoms, such as proptosis or other signs of thyroid eye disease. This is more commonly associated with differentiated thyroid cancers, including papillary thyroid carcinoma.

Age group

Associated comorbidity

Associated activity

Acuity of presentation

Differential Diagnoses

Papillary thyroid carcinoma

Medullary thyroid carcinoma

Hashimoto’s thyroiditis

Follicular adenoma

Laboratory Studies

Imaging Studies

Procedures

Histologic Findings

Staging

Treatment Paradigm

The treatment paradigm for follicular thyroid carcinoma typically involves a multidisciplinary approach that may include surgery, radioactive iodine therapy, and, in some cases, thyroid hormone replacement therapy. The specific treatment plan depends on factors such as the stage of the cancer, the extent of the disease, and individual patient characteristics.

by Stage

by Modality

Chemotherapy

Radiation Therapy

Surgical Interventions

The primary treatment for follicular thyroid carcinoma is surgical removal of the tumor and, in many cases, the entire thyroid gland. Depending on the extent of the disease, removal of nearby lymph nodes may also be necessary. Surgical treatment aims to remove as much of the cancerous tissue as possible.

Hormone Therapy

Immunotherapy

Hyperthermia

Photodynamic Therapy

Stem Cell Transplant

Targeted Therapy

Palliative Care

Intervention with a procedure

Thyroid Hormone Replacement Therapy 

Following surgery and radioactive iodine therapy, patients often require lifelong thyroid hormone replacement therapy (thyroxine or T4). The goal is to maintain thyroid hormone levels within the normal range, as the removal of the thyroid gland and the radioactive iodine treatment may lead to hypothyroidism. 

Radioactive Iodine Therapy (I-131 Therapy) 

After surgery, patients may undergo radioactive iodine therapy. Thyroid cells, including cancerous cells, absorb iodine. Radioactive iodine is administered, and the absorbed radiation helps eliminate any remaining thyroid tissue or cancer cells. This therapy is particularly effective for treating residual thyroid tissue and preventing recurrence. 

Medication

Media Gallary

References

Follicular thyroid carcinoma

Updated : May 20, 2024




Follicular thyroid cancer is a type of thyroid cancer that originates from the follicular cells of the thyroid gland. The thyroid gland in the front of the neck produces hormones that regulate metabolism. Thyroid cancers are relatively uncommon but are generally treatable. Follicular thyroid cancer arises from the follicular cells of the thyroid gland. These cells produce thyroid hormones, primarily thyroxine (T4) and triiodothyronine (T3).

Like many cancers, the exact cause of follicular thyroid cancer is often unknown. However, certain risk factors may increase the likelihood of developing thyroid cancer, including a family history of thyroid cancer, exposure to high levels of radiation, and certain genetic conditions. Follicular thyroid cancer is characterized by the formation of follicles or structures resembling follicles. The cancer cells may invade blood vessels and, in some cases, spread to distant organs, particularly the lungs and bones.

Follicular thyroid carcinoma represents a smaller proportion of thyroid cancers compared to papillary thyroid carcinoma, but it is one of the more common types. The incidence varies geographically, with higher rates reported in certain regions, including some areas with iodine deficiency.

Follicular thyroid carcinoma can occur at any age, but it is more commonly diagnosed in adults. The incidence tends to increase with age. There is generally a higher incidence in women compared to men. The prevalence of certain risk factors, such as iodine deficiency, may contribute to regional differences in the incidence of follicular thyroid carcinoma.

Follicular thyroid carcinoma arises from the follicular cells of the thyroid gland, specifically the cells that line the thyroid follicles. Normal thyroid follicular cells produce thyroid hormones (T3 and T4) that play a crucial role in regulating metabolism. Genetic mutations are often implicated in the development of follicular thyroid carcinoma. Specific genetic alterations may drive the transformation of normal thyroid cells into cancerous cells.

Common mutations include alterations in genes such as the RAS and PAX8/PPARγ genes. Follicular thyroid carcinoma typically presents as a well-defined tumor within the thyroid gland. The tumor often forms follicles or structures resembling normal thyroid follicles, and these cancerous follicles may invade nearby tissues. In some cases, follicular thyroid carcinoma may invade blood vessels. This vascular invasion can facilitate the spread of cancer cells to other parts of the body, particularly the lungs and bones.

Metastasis is a critical aspect of the pathophysiology of cancer. Follicular thyroid carcinoma may metastasize to distant organs through the bloodstream. Distant metastases, especially to the lungs, are a characteristic feature of more advanced cases. Angiogenesis, the formation of new blood vessels, is often promoted by cancer cells to ensure a blood supply for the growing tumor. The development of new blood vessels facilitates the nourishment of cancer cells and supports their ability to invade and metastasize. Follicular thyroid carcinoma is often classified into stages based on the size of the tumor, extent of invasion, and presence of metastasis.

Genetic Factors:

There is evidence that genetic factors play a role in the development of follicular thyroid carcinoma. Specific genetic mutations, such as mutations in the RAS gene and alterations involving the PAX8/PPARγ gene, have been associated with follicular thyroid carcinoma.

Iodine Deficiency:

Iodine is an essential element for the production of thyroid hormones. Chronic iodine deficiency has been linked to an increased risk of thyroid cancer, including follicular thyroid carcinoma. However, in some well-nourished populations, follicular thyroid carcinoma can still occur.

Radiation Exposure:

Exposure to ionizing radiation, especially during childhood, is a well-established risk factor for thyroid cancer. Individuals exposed to radiation from nuclear accidents, therapeutic radiation treatments, or certain occupational exposures may have an elevated risk of developing follicular thyroid carcinoma.

Age and Gender:

The risk of follicular thyroid carcinoma increases with age and is more common in adults. Women tend to be more commonly affected than men.

Follicular thyroid carcinoma often presents as a thyroid nodule. Palpation or imaging studies may reveal the presence of a lump in the thyroid gland. Swelling or enlargement of the thyroid gland, leading to changes in the appearance of the neck, may be observed. Compression of nearby structures by the tumor can lead to symptoms such as difficulty swallowing or hoarseness.

Follicular thyroid carcinoma may affect thyroid hormone production, leading to symptoms of hypothyroidism or hyperthyroidism. However, these symptoms are often subtle. While thyroid cancers, including follicular thyroid carcinoma, are often painless, some individuals may experience discomfort or pain in the neck area.

In advanced cases with metastasis, individuals may experience systemic symptoms such as unintentional weight loss, fatigue, or changes in appetite. The onset of symptoms can vary. In some cases, follicular thyroid carcinoma may be asymptomatic and discovered incidentally during a routine examination or imaging study. Some individuals may have persistent symptoms for an extended period, while others may notice more rapid changes.

Palpation of the thyroid gland may reveal the presence of a nodule or mass. Follicular thyroid carcinoma often presents as a solitary thyroid nodule. The thyroid gland may be enlarged, leading to an increased size of the neck. This enlargement could be due to the presence of a tumor. Follicular thyroid carcinomas may have a firm or hard consistency compared to benign thyroid nodules.

However, it is important to note that physical examination alone cannot definitively distinguish between benign and malignant nodules. Thyroid nodules are typically non-tender. Tenderness may be associated with inflammation or other thyroid conditions but is less commonly observed in thyroid cancer. Large thyroid tumors may cause compression of the trachea, leading to tracheal deviation. This can result in respiratory symptoms such as difficulty breathing.

Compression of the recurrent laryngeal nerve by a thyroid tumor can lead to hoarseness or changes in voice quality. In some cases, thyroid cancers may be associated with eye symptoms, such as proptosis or other signs of thyroid eye disease. This is more commonly associated with differentiated thyroid cancers, including papillary thyroid carcinoma.

Papillary thyroid carcinoma

Medullary thyroid carcinoma

Hashimoto’s thyroiditis

Follicular adenoma

The treatment paradigm for follicular thyroid carcinoma typically involves a multidisciplinary approach that may include surgery, radioactive iodine therapy, and, in some cases, thyroid hormone replacement therapy. The specific treatment plan depends on factors such as the stage of the cancer, the extent of the disease, and individual patient characteristics.

The primary treatment for follicular thyroid carcinoma is surgical removal of the tumor and, in many cases, the entire thyroid gland. Depending on the extent of the disease, removal of nearby lymph nodes may also be necessary. Surgical treatment aims to remove as much of the cancerous tissue as possible.

Thyroid Hormone Replacement Therapy 

Following surgery and radioactive iodine therapy, patients often require lifelong thyroid hormone replacement therapy (thyroxine or T4). The goal is to maintain thyroid hormone levels within the normal range, as the removal of the thyroid gland and the radioactive iodine treatment may lead to hypothyroidism. 

Radioactive Iodine Therapy (I-131 Therapy) 

After surgery, patients may undergo radioactive iodine therapy. Thyroid cells, including cancerous cells, absorb iodine. Radioactive iodine is administered, and the absorbed radiation helps eliminate any remaining thyroid tissue or cancer cells. This therapy is particularly effective for treating residual thyroid tissue and preventing recurrence.