Endocrine Abstracts

Background: and ObjectiveThyroid collision tumors are extremely rare, accounting for just around 1% of all thyroid carcinomas. The objective of this study is to enhance our understanding of the clinical characteristics of these infrequently reported occurrences. In our study, we evaluated the clinical features of medullary thyroid carcinoma (MTC) that existed synchronously with papillary thyroid carcinoma (PTC).

Methods: We performed a retrospective analysis of 21 patients who were diagnosed between 2010 and 2022 at the Department of Endocrinology, Ankara University. The demographics and clinical characteristics of the patients are the variables examined in this study.

Results: Mean age at diagnosis was 56.6±12.4 years, %85.7 were women, and the follow-up duration was 34.4 mo (range 6–96). 85.7% of patients had a single focal MTC, the median MTC focus was 8 mm (range 0.6–56), 47.6% was localized on the left lobe, and 9.5% was multifocal in both lobes. 57.1% of patients had a single focal PTC, the median PTC focus was 5.5 mm (range 0.1–17), right and left lobe localization was equal (23.8% vs 23.8%) but 38.1% was multifocal in both lobes, common PTC subtypes: classical variant and mPTC (28.6% and 23.8%). The RET mutation status of twelve was unknown; six were negative, two had the S891A mutation, and one had the C618A mutation. Preoperative calcitonin levels were correlated with preoperative CEA (carcinoembryonic antigen) and postoperative calcitonin levels were statistically significant but not related to postoperative CEA levels (r=0.827, 0.666, and 0.545 respectively). MTC foci diameter correlated with preoperative CEA and calcitonin levels and also postoperative CEA ve calcitonin levels (r=0.905, 0.871, 0.588, and 0.626 respectively). PTC foci count negatively correlated with preoperative CEA levels (r=0.620).

Conclusion: This study provides significant value in terms of improving awareness and advancing our knowledge and treatment of these uncommon carcinomas.