Objective: This report reports a case of primary uterine lymphoma that was initially misdiagnosed as uterine fibroids/uterine sarcomas. Through case report, the recognition of primary uterine lymphoma is strengthened. If MRI shows very high DWI signal in the tumor in future clinical work, it should be considered whether it is lymphoma.Background: A 64-year-old woman who was found to have an abdominal mass on ultrasound was initially misdiagnosed with a uterine fibroid/uterine sarcoma. Clinical evidence: Pelvic MRI showed multiple soft tissue mass shadows in the pelvic cavity, and the larger shadows were approximately 14.2 cm × 9.7 cm × 15.6 cm, with clear boundaries dominated by an iso-long T1 and slightly longer T2, locally visible nodular long T2 and short T2 signal foci, and obvious high signals on DWI and decreased ADC signals. The enhancement of the densification was obviously non-uniform. The immunohistochemical results were positive for CD20, LCA, PAX-5+, CD43 +, c-myc, bcl2 and bcl6 and negative for SAM, Desmin, Myo D1, MPO, CD99, CD30, CD23, S-100, and CD10. The majority (90%) of tumor cells were positive for Ki-67. The diagnosis was a diffuse large b-cell lymphoma. Preoperative diagnosis of primary lymphoma of the uterus is difficult in clinical situations. Primary female genital system lymphoma (PFGSL) is a rare disease that is mostly associated with non-Hodgkin's lymphoma, usually diffuse large b-cell lymphoma (DLBCL). The majority of primary uterine DLBCL originates from endometrial stroma.