Malignancy Rates in Thyroid Nodules Classified as Bethesda Categories III and IV: Retrospective Data from a Tertiary...

Area of Science:

• Endocrinology
• Oncology
• Cytopathology

Background:

• Thyroid fine needle aspiration (FNA) is crucial for diagnosing thyroid nodules.
• The Bethesda System categorizes FNA results, with categories III and IV indicating uncertain or suspicious findings.
• Treatment decisions for Bethesda categories III and IV nodules involve varying malignancy risks.

Purpose of the Study:

• To determine the association between Bethesda categories III and IV and malignancy rates.
• To analyze malignancy rates in patients treated at a tertiary cancer center where surgery is standard for these categories.

Main Methods:

• Retrospective analysis of 615 thyroid nodules (582 patients).
• Nodules were classified as Bethesda category III (478) or IV (137).
• Correlation between FNA cytology and histopathology, including incidentally detected carcinomas, was established.

Main Results:

• Malignancy rates were 15.7% for Bethesda III and 16.8% for Bethesda IV target nodules.
• When incidental carcinomas were included, malignancy rates effectively doubled.
• Contralateral lobe carcinomas were found in over 50% of patients with incidentally detected cancers.

Conclusions:

• Bethesda categories III and IV demonstrate significant malignancy rates (16-17%).
• The detection of incidental carcinomas substantially increases the overall malignancy yield.
• These findings support careful evaluation and management of nodules within these Bethesda categories.