Anaplastic and poorly differentiated thyroid carcinomas at intervention sites: implications of track seeding and the importance of follow-up monitoring- report of two cases.

[INTRODUCTION] Radiofrequency ablation (RFA) is widely used to treat benign thyroid nodules. While pre-ablation cancer screenings can produce false-negatives, tumor seeding is rare, and aggressive thyroid cancers following RFA have not been reported. We present two cases of potential track seeding after RFA.

[CASE REPORT] The first patient is a 56-year-old female who developed anaplastic thyroid cancer, while the second is a 61-year-old female diagnosed with poorly differentiated thyroid cancer. Both had a history of RFA for presumed benign nodules, with cancer identified at the intervention sites.

[CONCLUSION] These cases highlight the need for thorough pre-treatment biopsy and careful needle handling during RFA. To date, no cases of cancer directly induced by RFA have been reported; therefore, it is likely that thyroid carcinoma coexisted at the time of the procedure or developed afterward. Early detection through regular follow-up could have prevented progression to aggressive disease. This emphasizes the importance of diligent post-procedural monitoring.