Objective  To summarize the ultrasound characteristics of primary thyroid lymphoma, and the causes of misdiagnosis and missed diagnosis.

Methods This study retrospectively analyzed the ultrasonic images and reports of 51 patients diagnosed with primary thyroid lymphoma at Guangdong Provincial People's Hospital from January 1, 2012 to August 31, 2023. The diagnosis was based on preoperative routine thyroid color ultrasound or pathological confirmation via surgical resection or core needle biopsy. The focus was on observing the thyroid parenchyma echogenicity and lesion characteristics during ultrasound examinations, including the size, echogenicity, shape, boundaries, presence of calcifications,cystic degeneration, coexistence with Hashimoto's thyroiditis, and involvement of cervical lymph nodes. The ultrasound findings were compared by pathology.

Results The ultrasound diagnosis results were compared with the pathological results, and the pathological results were the gold standard, which met the primary thyroid lymphoma for 23 cases. There were 17 cases misdiagnosed and 11 cases missed diagnosis.

Conclusion Parenchymal lesions, extremely hypoechoic, enhanced posterior echo, slightly stronger echo in the cord, irregular morphology, rare calcification, no cystic degeneration, associated with cervical lymphadenopathy, thyroid accompanied by Hashimoto's thyroiditis, etc. There is high clinical value with these ultrasonographic features in diagnosing primary thyroid lymphoma.