Research Article: Morphological Study of Hashimoto Thyroiditis in Fine Needle Aspiration Cytology Specimens

Abstract:
Hashimoto’s thyroiditis is the second most common cause of hypothyroidism worldwide, second to inadequate iodine intake. But in developed countries and in areas where dietary iodine intake is sufficient, it is the most common cause of hypothyroidism., It is to times more common in females. Hashimoto’s thyroiditis usually presents as diffuse, symmetric, and painless enlargement of thyroid, but enlargement may be nodular also. In early stages, patients are euthyroid, or few patients may have thyrotoxicosis (Hashitoxicosis) due to disruption of thyroid follicles leading to release of stored thyroid hormones. As the disease evolves, there is gradually progressive destruction of thyroid follicles, and patient presents with subclinical hypothyroidism and later with overt hypothyroidism.– Anti-thyroid peroxidase (anti-TPO) antibodies, anti-thyroglobulin antibodies (Tg Ab) and TSH receptor blocking antibodies can be present in the disease. Among these, anti-TPO antibodies are the most common which are present in % of patients. However, in euthyroid patients, its sensitivity is only %. Because these antibodies are also present in Graves disease, positive test should be confirmed by fine needle aspiration cytology especially if the patient has hyperthyroidism. Tg Ab is markedly elevated in the early phase of Hashimoto thyroiditis, but in the late stages of the disease, it may disappear. On the other hand, TPO Ab is only mildly elevated in the early phase, but it persists for many years unlike Tg Ab. Patients with atrophic thyroiditis and mothers of athyreotic cretins have elevated levels of TSH-R blocking antibody. While their presence is helpful in diagnosis, these are not hundred percent specific for Hashimoto thyroiditis, because moderate titers are seen in Graves disease, multinodular goiter, and thyroid neoplasm; and low titers are found in the elderly., On the other hand, fine needle aspiration cytology (FNAC) has very good sensitivity and specificity for the diagnosis of Hashimoto thyroiditis in patients with all types of thyroid function and autoantibody status.– In the cytomorphologic diagnosis of the disease, follicular epithelial cells, lymphoid cells, multinucleated giant cells, Hurthle cells, epithelioid cells, and amount of colloid are analyzed in detail and the diagnostic categorization is done according to “The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC)”. The aim of this study is to describe cytomorphologic characteristics in patients of Hashimoto thyroiditis and compare them with other studies. During literature review, it was found that the detailed study on multinucleated giant cells was lacking. Past studies have described only the presence or absence of the giant cells but not their size and number of nuclei in them. This information on size and number of nuclei in a giant cell is important from the diagnostic point of view because these cells are present in other thyroid diseases as well mainly subacute thyroiditis and papillary carcinoma. The current study aims to fill that lacuna in the cytomorphology of Hashimoto thyroiditis.

Introduction:
Hashimoto’s thyroiditis is the second most common cause of hypothyroidism worldwide, second to inadequate iodine intake. But in developed countries and in areas where dietary iodine intake is sufficient, it is the most common cause of hypothyroidism. , It is to times more common in females. Hashimoto’s thyroiditis usually presents as diffuse, symmetric, and painless enlargement of thyroid, but enlargement may be nodular also. In early stages, patients are euthyroid, or few patients may have thyrotoxicosis…

Read more