Aggressive angiomyxoma (AA) is a rare mesenchymal tumor of the lower pelvis and genital region, characterized by local infiltration and frequent, even multiple recurrences. In the present paper a case of a small-sized AA of the vagina, in a 55-year-old woman is reported. We describe the histological appearance and the immunohistochemical phenotype of this tumor and discuss its differential diagnosis from other mesenchymal lesions occurring in the pelvic and genital region. Furthermore, we attempt to enlighten the possible mechanisms that govern the pathogenesis and the biological behavior of this "mysterious" neoplasm.