Primary thyroid lymphoma (PTL) is a rare extranodal lymphoma closely associated with Hashimoto’s thyroiditis. Because the sonographic features of PTL overlap with those of anaplastic thyroid carcinoma, papillary thyroid carcinoma, and inflammatory thyroid diseases, early diagnosis remains challenging. This paper reviews the epidemiology, clinicopathological features, and ultrasonic manifestations of PTL, focusing on the roles of multimodal ultrasound and ultrasound-guided core needle biopsy in early identification, subtype prediction, and progression monitoring. It aims to provide differential diagnostic insights for sonologists and references for clinical decision-making and therapeutic efficacy evaluation.