Three methods are currently used to evaluate thyroid nodules. These are fine needle aspiration or FNA, thyroid scan and ultrasound. Of these three, the initial FNA is said to be more diagnostically useful and cost effective. Although ultrasound may be able to detect nodules that cannot be detected by palpation, it is still indistinguishable from malignant nodules and benign nodules. Thyroid scans can also be misleading when explaining malignant tumors of the thyroid nodules.

Fine needle aspiration biopsy is a technique in which a tissue sample is aspirated using a fine needle for evaluation. For surface tissue such as the thyroid gland, breast or prostate, the needle is unguided, but for deeper tissue, the needle must be radiologically guided.

Normal thyroid under the microscope

Unlike other endocrine glands, the thyroid is unique because it provides extracellular storage for products within the cyst. from

Hair follicle. These follicles contain thyroid hormones that are good enough for weeks. They are almost spherical and surrounded by a single layer of cubic cells. These follicles range in diameter from 0.2 to 0.9 mm and are filled with a substance called from

colloid.

Some cytologists believe that there must be at least six groups of 10 to 20 cells of follicular cells on two slides so that the thyroid biopsy meets benign conditions. If there are other signs of malignancy in the sample, a diagnosis of malignancy can be made when there are fewer cells.

Cytopathological features

Fine needle aspiration of the thyroid gland can be difficult and challenging because the amount of tissue on the slide used for examination may depend on the method of aspiration. However, the assessment of thyroid tissue should include the following:

• The presence or absence of follicles
• Cell size
• Characteristics of stained cells
• Organizational polarity. This should only be considered in cell block specimens.
• Nuclear trough and/or nuclear clearance
• The presence of nucleoli
• The presence and type of colloid
• Monotonous population of follicles or Hurthle cells
• Lymphocyte

Benign lesion

Almost 70% of thyroid masses are benign. Although the patient's clinical symptoms may be beneficial for benign lesions, FNA does not mean that FNA should be excluded from the examination. These are the following clinical features of benign thyroid disease:

• Sudden onset of pain and tenderness may indicate bleeding as a benign adenoma or cyst or subacute granulomatous thyroiditis, respectively. However, bleeding to cancer may have similar symptoms.
• Symptoms indicate hyperthyroidism or autoimmune thyroiditis [Hashimoto's disease].
• Family history of benign sarcoidosis, Hashimoto's disease or autoimmune thyroiditis.
• Smooth, soft, easy to move nodules.
• More nodules.
• The midline nodules above the hyoid bone move up and down as the tongue protrudes, most likely a thyroglossal cyst.

The cytological and laboratory characteristics of benign thyroid nodules are as follows:

• There are abundant hydrocolloids.
• Foam macrophages.
• Solid nodules of cyst or cyst degeneration.
• Hyperplastic nodules.
• The TSH level is abnormal.
• Lymphocyte and/or high thyroid peroxidase antibody levels. These may indicate Hashimoto's disease or a rare lymphoma.

Malignant lesion

• Papillary carcinoma

Papillary carcinoma accounts for about 80% of thyroid malignant lesions. Malignant tumors of this type include mixed papillary and follicular variants, such as high cell variants and sclerotic variants. Two or more of the following cytological features suggest papillary carcinoma:

• Nuclear inclusions, "clear", "frosted glass" or "orphan" core
• Nuclear "groove"
• Overlapping core
• Salmonella [rarely seen]
• Papillary protrusion with fibrous vascular core
• "rope" colloid

Follicular or Hurthle cell tumor

The expression of lesions in this diagnostic category may be characteristic of malignant tumors, but not a true diagnosis. Factors that point to malignant tumors include men, with nodules more than 3 cm in size and older than 40 years.

A clear diagnosis requires a histological examination of the nodules to observe capsular or vascular invasion. To date, no genetic, histological or biochemical tests have been routinely used to distinguish between benign or malignant lesions of this category. Several studies have shown that thyroid peroxidase expression measured by the monoclonal antibody MoAb 47 improves the specificity of correctly distinguishing between benign and malignant tumors in FNA specimens. Galectin-3 was also observed to be highly and diffusely expressed in follicular cell tumors, but minimally expressed only under benign conditions.

Cytological or histological features of follicular malignancies include:

• Minimum amount of free colloid
• High-density cell population of follicles or Hurthle cells
• Microfollicles

In cytology, these lesions can be reported as:

• "Hurthle Cell Tumor"
• "Suspicious follicular tumor"
• "follicular tumors/lesions"
• "Uncertain" or "non-diagnosed"

Medullary carcinoma

Fifteen percent of thyroid malignancies are defined in this category. This type of thyroid malignancy should be suspected in patients with medullary carcinoma or multiple endocrine neoplasia type 2.

Cytological or histological features include the following:

• Spindle-shaped cells with eccentric nuclei
• Positive calcitonin staining
• Amyloid
• Nuclear inclusions [common]

Anaplastic cancer

In less than one percent of patients with malignant thyroid disease, anaplastic cancer is diagnosed. This type of malignancy is more common in elderly patients with rapidly growing thyroid masses. These patients may have been slowly gaining weight over the years. Importantly, the treatment of limited anaplastic cancer is distinguished from thyroid lymphoma, which has ready-made treatments.

Cytological features of anaplastic cancer include:

• Extreme cell polymorphism
• Multinucleated cell
• Giant cell

Thyroid lymphoma

This is a rare thyroid malignancy. Rapid growth of the neck mass in the thyroid gland in elderly patients, especially in patients with Hashimoto's thyroiditis, suggests thyroid lymphoma. It can be further pointed out that the cytological features of this diagnosis include:

• Simplex pattern of lymphocytes
• Positive B cell immunotype

Although thyroid fine needle aspiration is an important technique for assessing thyroid disease, patients are always free to ask for a second opinion, especially for serious things like thyroid cancer. As mentioned earlier, it is also important to check that pathologists or cytologists distinguish between different malignancies. A quick and correct diagnosis can explain the difference between quality of life, disability and even death.

Diagnostic classification of thyroid fine needle aspiration was originally published on Spring