MODERN CLASSIFICATION AND DIFFERENTIAL DIAGNOSIS OF THYROID CARCINOMA: A SYSTEMATIC REVIEW

Introduction: Thyroid cancer is the most common endocrine malignancy. Although most thyroid nodules are benign, accurate differentiation from malignant lesions is critical for treatment decisions and prognosis. Methods: A systematic literature search was conducted in PubMed, Scopus, and Google Scholar (2015-2024). Keywords included "thyroid cancer diagnosis", "Bethesda classification", "fine needle aspiration biopsy", "papillary thyroid carcinoma", and "molecular testing". Quality assessment used QUADAS-2. Results: Analysis demonstrates that ultrasound, fine-needle aspiration biopsy, and the Bethesda cytological classification system remain the cornerstone of thyroid nodule evaluation. Molecular testing significantly improves diagnostic accuracy, especially in indeterminate cytological cases (Bethesda III-IV). Key genetic mutations include BRAF V600E (29-69% in papillary), RAS (40-50% in follicular), and RET (~25% in hereditary medullary carcinoma). Conclusion: Accurate diagnostic evaluation using modern clinical, cytological, and molecular methods significantly improves patient outcomes and allows individualized management of thyroid cancer.