Uterine leiomyosarcoma with osteosarcomatous dedifferentiation

Leiomyosarcoma is the most common sarcoma of the uterine corpus, however, uterine dedifferentiated leiomyosarcoma remains a poorly characterized entity. Dedifferentiation in leiomyosarcoma can be defined as the occurrence of a high-grade undifferentiated sarcoma in association with a lower-grade sarcoma that demonstrates morphologic and immunophenotypic evidence of myogenic differentiation. The occurrence of extensive heterologous elements in the high-grade area can be problematic confusing the tumor with other more specific types of high-grade sarcomas. Available reports of this entity indicate aggressive biological behavior and poor prognosis. Herein, we describe a case of a 35-year-old woman who presented with menorrhagia and underwent a total abdominal hysterectomy with bilateral salpingo-oophorectomy. The histopathological examination of the surgical specimen revealed features of a low-grade leiomyosarcoma juxtaposed to a high-grade sarcoma with osteosarcomatous differentiation.