Intravascular large B-cell lymphoma (IVLBCL) is a rare subtype of non-Hodgkin lymphoma that infiltrates the lumina of small- to medium-sized vessels without causing lymphadenopathy or masses. Due to the wide variety of organ involvement and clinical manifestations of this disease, intravascular large B cell lymphoma has been described as the “great imitator”. Many of these cases are not diagnosed until autopsy due to the unusual presentations and the rarity of this disease. Physicians must understand that biopsy with immunohistochemistry is the current best modality for early and accurate diagnoses of intravascular large B-cell lymphoma. Only eight uterine intravascular large B-cell lymphoma cases have ever been reported. In this case, abnormal uterine bleeding led to an endometrial biopsy detecting the lymphoma. Later an invasive endometrioid adenocarcinoma was identified after remission of the lymphoma.