Medullary thyroid carcinoma diagnosis based on microRNA analysis: a case report.

PURPOSE: Medullary thyroid cancer (MTC) is primarily diagnosed through calcitoninlevel analysis and RET mutation status. In their absence, MTC diagnosis may notoccur until after surgery, requiring a completion thyroidectomy after initial lobectomy.The authors present the first reported prospective case of MTC diagnostic suspiciondriven primarily by microRNA (miRNA) profiling.

CASE PRESENTATION: A 42-year-old male with an incidentally found thyroid nodule underwent FNA, revealing Bethesda IV cytology. ThyGeNEXT® sequencing showedno mutations; ThyraMIR®v2 profiling demonstrated a 91% match pattern favoringMTC. Subsequent labs noted elevated calcitonin (273 pg/mL). The patient underwent total thyroidectomy and central neck dissection. Histology confirmed MTC with calcitonin, INSM1, and S100 protein positivity.

CONCLUSION

This case demonstrates the potential of miRNA profiling as a stand-alonediagnostic adjunct in indeterminate thyroid nodules, highlighting its role in preventingdelayed diagnosis and improving surgical planning.