Introduction

Thyroid cancer is a type of cancer that affects the thyroid gland, a small butterfly-shaped organ located in the front of the neck. It is one of the most common endocrine malignancies and can affect people of all ages and genders. While most cases of thyroid cancer are treatable, some can be more difficult to diagnose and treat. The histology of thyroid cancer can provide valuable insight into the diagnosis and prognosis of the disease. This article reviews the histology of thyroid cancer, including common types, cell types, histological patterns, and prognostic factors.

Types of Thyroid Cancer

Thyroid cancer can be classified into four major types. These are papillary, follicular, medullary, and anaplastic thyroid cancer.

• Papillary Thyroid Cancer: Papillary thyroid cancer (PTC) is the most common type of thyroid cancer, accounting for around 80% of all cases. It is typically slow-growing and usually affects adults aged 30 to 50. PTC is often asymptomatic and can be diagnosed from a biopsy of the affected area.

• Follicular Thyroid Cancer: Follicular thyroid cancer (FTC) is the second most common type of thyroid cancer, accounting for 10-15% of all cases. It typically affects adults aged 45 to 65 and is usually slow-growing. FTC is usually asymptomatic and can be diagnosed from a biopsy of the affected area.

• Medullary Thyroid Cancer: Medullary thyroid cancer (MTC) is the third most common type of thyroid cancer, accounting for around 3-5% of all cases. It typically affects adults aged 45 to 65 and is usually slow-growing. MTC is usually asymptomatic and can be diagnosed from a biopsy of the affected area.

• Anaplastic Thyroid Cancer: Anaplastic thyroid cancer (ATC) is the rarest type of thyroid cancer, accounting for less than 1% of all cases. It usually affects adults aged 65 and over and is usually fast-growing. ATC is usually symptomatic and can be diagnosed from a biopsy of the affected area.

Cell Types

Thyroid cancer can be further classified based on the type of cells that are present in the tumor. Common cell types include:

• Follicular Cells: Follicular cells are the most common type of cell in papillary and follicular thyroid cancer. They are round or oval-shaped cells with a dark-staining nucleus and a light-staining cytoplasm. Follicular cells can be further divided into two subtypes: oncocytic cells and oxyphilic cells.

• Oncocytic Cells: Oncocytic cells are found in papillary and follicular thyroid cancer and are typically round or oval-shaped cells with a dark-staining nucleus and a light-staining cytoplasm. They may have a granular appearance and may contain cytoplasmic inclusions.

• Oxyphilic Cells: Oxyphilic cells are found in papillary and follicular thyroid cancer and are typically round or oval-shaped cells with a dark-staining nucleus and a light-staining cytoplasm. They may have a granular appearance and may contain cytoplasmic inclusions.

• Hürthle Cells: Hürthle cells are found in follicular thyroid cancer and are typically oval-shaped cells with a dark-staining nucleus and a light-staining cytoplasm. They may have a granular appearance and may contain cytoplasmic inclusions.

• Clear Cells: Clear cells are found in follicular thyroid cancer and are typically round or oval-shaped cells with a dark-staining nucleus and a light-staining cytoplasm. They may have a granular appearance and may contain cytoplasmic inclusions.

• Medullary Cells: Medullary cells are found in medullary thyroid cancer and are typically round or oval-shaped cells with a dark-staining nucleus and a light-staining cytoplasm. They may have a granular appearance and may contain cytoplasmic inclusions.

• Squamous Cells: Squamous cells are found in anaplastic thyroid cancer and are typically oval-shaped cells with a dark-staining nucleus and a light-staining cytoplasm. They may have a granular appearance and may contain cytoplasmic inclusions.

Histological Patterns

Thyroid cancer can also be classified based on histological patterns. Common histological patterns include:

• Solid Pattern: The solid pattern is a common histological pattern found in papillary and follicular thyroid cancer. It is characterized by sheets and clusters of cells that lack any distinct architectural pattern.

• Psammoma Bodies: Psammoma bodies are spherical structures that are often found in papillary and follicular thyroid cancer. They are composed of calcified material and are often a sign of malignancy.

• Trabecular Pattern: The trabecular pattern is a common histological pattern found in follicular thyroid cancer. It is characterized by sheets of cells that have a branching or trabecular pattern.

• Cribriform Pattern: The cribriform pattern is a common histological pattern found in follicular thyroid cancer. It is characterized by sheets of cells that have a lacy or cribriform pattern.

• Follicular Pattern: The follicular pattern is a common histological pattern found in follicular thyroid cancer. It is characterized by sheets of cells that have a follicular pattern.

• Spindle Cell Pattern: The spindle cell pattern is a common histological pattern found in anaplastic thyroid cancer. It is characterized by sheets of cells that have a spindle-like shape.

Prognostic Factors

The prognosis for thyroid cancer depends on a number of factors, including the type of cancer, the stage of the cancer, and the histological patterns present in the tumor. Other prognostic factors include the size of the tumor, the presence of lymph node involvement, and the presence of distant metastases.

Conclusion

Thyroid cancer is a type of cancer that affects the thyroid gland. The histology of thyroid cancer can provide valuable insight into the diagnosis and prognosis of the disease. This article has reviewed the histology of thyroid cancer, including common types, cell types, histological patterns, and prognostic factors.