Abstract: Primary breast lymphoma (PBL) is a rare malignant extranodal tumor originating in the mammary gland. The clinical manifestations of PBL are often lack of specificity, and the course of the disease progresses rapidly. Early diagnosis is beneficial to improve the prognosis of patients. As an increasingly mature molecular imaging technology, ¹⁸F-fluorodeoxyglucose (FDG) PET combined with CT or MRI has high diagnostic sensitivity and accuracy for PBL, and has important value in cancer staging and efficacy evaluation. This paper reviews the application progress of ¹⁸F-FDG PET in the diagnosis and treatment of PBL.