Role of Frozen Section in Categorization of Thyroid Follicular Neoplasm

Role of Frozen Section in Categorization of Thyroid Follicular Neoplasm

The goal of this prospective study is to assess the effectiveness of frozen section in distinguishing between benign and malignant tumors in the category of follicular thyroid neoplasm to prevent over-surgery for benign follicular neoplasm (lobectomy Vs total thyroidectomy).

The main questions, it aims to answer are:

The follicular neoplasm is benign or malignent? how far is FNAC valid and accurate? Researchers will compare the results of frozen section and paraffin embedded sections to evaluate the validity and accuracy of FNAC.

Thyroid tumors are the most common endocrine neoplasms, with their incidence steadily rising over the past few decades, reaching approximately 8.7 cases per 100,000 people annually in Europe. The majority of thyroid tumors are benign accounting for over 90% of cases, whereas malignant thyroid tumors are relatively less common. Thyroid cancer represents 1-2% of all newly diagnosed malignancies worldwide, with papillary thyroid carcinoma (PTC) being the most prevalent (80%) followed by follicular thyroid carcinomas (FTC) (15%). Fine needle aspiration cytology (FNAC) is the primarily diagnostic tool for thyroid nodule. However, its accuracy in distinguishing between benign and malignant follicular neoplasms is limited, necessitating further histopathological evaluation. The Bethesda system classifies FNAC results into six categories, with follicular neoplasm/suspicious for follicular neoplasm (category IV) carrying a moderate risk of malignancy. Differentiating between benign and malignant follicular neoplasms requires assessing capsular and vascular invasion. Intraoperative frozen section (FS) has been used for decades to provide rapid histologic assessment guiding the extent of surgery (lobectomy Vs total thyroidectomy). However, its utility remains controversial due to variability in diagnostic accuracy and cost-effectiveness. The recent 5th edition of the WHO classification (2023) categorizes follicular-derived thyroid tumors into benign, low-risk and malignant neoplasms, further refining diagnostic criteria. This study aims to evaluate the accuracy of FNAC and FS in diagnosing follicular thyroid neoplasms, optimizing surgical decisions and reducing unnecessary total thyroidectomies in benign cases.

Inclusion Criteria:

• Cases presented with a thyroid nodule, diagnosed as "follicular neoplasm" (Bethesda category IV) by fine needle aspiration cytology, and underwent hemi-thyroidectomy.

Exclusion Criteria:

• Cases with thyroid nodule and diagnosed by fine needle aspiration cytology as non-neoplastic lesions, suspicious for malignancy or as malignant.