From the Guidelines
Hürthle cell metaplasia of the thyroid is a benign condition that requires monitoring but not specific treatment for the metaplasia itself. This condition is characterized by the transformation of normal thyroid follicular cells into larger cells with abundant granular cytoplasm, known as Hürthle cells or oncocytes, often in response to inflammation, autoimmune processes, or radiation exposure to the thyroid gland 1. The most common cause is Hashimoto's thyroiditis, an autoimmune disorder where the immune system attacks the thyroid. It's crucial to distinguish Hürthle cell metaplasia from Hürthle cell neoplasms, which can be benign or malignant.
Key points about Hürthle cell metaplasia include:
- It is not cancerous by itself but can be associated with conditions that may lead to malignancy.
- The diagnosis and management of the underlying condition causing the metaplasia are essential.
- Molecular diagnostics are not recommended for Hürthle cell neoplasms, as they may not perform well for these types of neoplasms 1.
- Clinical risk factors, sonographic patterns, and patient preference can help determine whether active surveillance or lobectomy is appropriate for Hürthle cell neoplasms.
Management of patients with Hürthle cell metaplasia typically involves:
- Regular thyroid function tests to monitor thyroid health.
- Occasional ultrasound imaging to ensure there's no development of more concerning thyroid conditions.
- Addressing the underlying condition, such as managing Hashimoto's thyroiditis, which may involve medication to regulate thyroid hormone levels or other treatments as necessary.
From the Research
Hürthle Cell Metaplasia of the Thyroid
Hürthle cell metaplasia of the thyroid refers to the presence of Hürthle cells in the thyroid gland, which can be found in both benign and malignant diseases of the thyroid 2, 3, 4.
Characteristics of Hürthle Cells
Hürthle cells are follicular-derived oncocytic cells that are characterized by their large size, abundant cytoplasm, and numerous mitochondria 5. They can be found in a variety of thyroid lesions, including nodular goiters, Hashimoto's thyroiditis, follicular adenomas, and follicular carcinomas 5.
Clinical Significance
The presence of Hürthle cells in fine needle aspiration cytology (FNAC) samples can be indicative of a neoplastic process, particularly if the cells exhibit certain cytomorphologic features such as high cellularity, scant colloid, and a high percentage of Hürthle cells 3, 4. However, the presence of Hürthle cells can also be found in benign lesions, and therefore, surgical resection is often necessary to differentiate between benign and malignant disease 2, 4.
Hürthle Cell Metaplasia in Chronic Lymphocytic Thyroiditis
Hürthle cell metaplasia is a common feature of chronic lymphocytic (Hashimoto) thyroiditis, particularly in adult patients 6. The frequency and severity of Hürthle cell metaplasia increase with age, with significant differences observed between pediatric and adult patients 6.
Key Features of Hürthle Cell Metaplasia
- Presence of Hürthle cells in the thyroid gland
- Can be found in both benign and malignant diseases of the thyroid
- Characterized by large size, abundant cytoplasm, and numerous mitochondria
- Often associated with chronic lymphocytic thyroiditis
- Increases with age, particularly in adult patients
- Can be indicative of a neoplastic process, particularly if certain cytomorphologic features are present 2, 3, 4, 5, 6