Aggressive angiomyxoma is a distinctive, locally aggressive tumor associated with a high risk of local recurrences that lacks metastatic potential. This tumor occurs mostly in the soft tissues of the pelvis and the perineum of adult women. It may rarely occur at less common sites, such as the vagina, urinary bladder, and soft tissue of the perineum and the perianal region in men, particularly the scrotum. We report a case of aggressive angiomyxoma presenting as an endometrial uterine polyp. To the best of our knowledge, the primary location of aggressive angiomyxoma within the uterine cavity has never been described. Immunohistochemical and ultrastructural findings support the conclusion that the progenitor cell displays myofibroblastic and fibroblastic features, with a capacity for smooth muscle differentiation.