Cause of misdiagnosis of medullary thyroid carcinoma as benign nodules and ultrasonic characteristics
FENG Guoqing
SU Rigu
LI Jiannan
BAI Fan
CHEN Li
Abstract：Objective To analyze the causes of misdiagnosis of medullary thyroid carcinoma(MTC),and to investigate its ultrasonic characteristics and clinical countermeasures to prevent misdiagnosis.Methods A retrospective analysis was conducted on the clinical data of 2 MTC patients who were misdiagnosed as benign thyroid nodules from May to August 2023.One patient visited the hospital due to the detection of a right thyroid lobe nodule one year ago.After ultrasound examination at another hospital,the patient was initially diagnosed with"thyroid adenoma".At one-year follow-up,the nodule increased in size.Re-examination by ultrasound showed microcalcification foci and rich blood flow signals.Fine-needle aspiration(FNA)biopsy showed positive immunostaining for calcitonin.Total thyroidectomy and central lymph node dissection were performed.Postoperative pathology confirmed MTC,and the misdiagnosis lasted 12 months.Thyroid hormone replacement therapy was given after the operation,and the patients were followed up for 12 months.Their thyroid function was stable and no signs of recurrence or metastasis were found.One patient presented with a left thyroid lobe nodule and two months of watery diarrhea,which was refractory to conventional anti-diarrheal therapy.After ultrasound examination at another hospital,it was proposed to be diagnosed as"nodular goiter".Combined with the patient's diarrhea symptoms,serum calcitonin detection and contrast-enhanced ultrasound examination suggested the possibility of MTC.Total thyroidectomy and bilateral lateral cervical lymph node dissection was performed.Postoperative pathology confirmed MTC with lymph node metastasis,and the misdiagnosis lasted 2.5 months.Targeted therapy with Vandetanib was administered after the operation.After a 6-month follow-up,the diarrhea symptoms were completely relieved,the serum calcitonin level dropped to the normal range,and no recurrence was observed in the neck ultrasound and enhanced CT examinations.Conclusion The ultrasound manifestations of MTC are easily confused with benign nodules.Microcalcification,rich blood flow and the"fast-in and fast-out"angiography mode are its important characteristics.For patients with diarrhea or elevated calcitonin,the possibility of MTC should be highly vigilant,and the combined detection of FNA and calcitonin can improve the accuracy of diagnosis.
Keywords：medullary thyroid carcinomamisdiagnosisthyroid noduleultrasound examinationfine-needle aspiration biopsycalcitonindifferential diagnosis
Publication Date：2025-12-28
Online Publishing Date：2026-01-16(First online date of this platform, not the publication date of the document)
Pages：6( 15-20 )