Undifferentiated Uterine Sarcoma: A Rare Cause of Pelvic Pain in Young Woman

We report a case of undifferentiated uterine sarcoma occurring in a 20-year-old woman presenting as a pelvic pain with a mass discovered at the physical examination. The tumor ruptured into the abdominal cavity. A total hysterectomy was performed. On the pathological examination, the uterine corpus presents a proliferation of markedly atypical spindle cells admixed with round cells and pleomorphic cells. The tumor deeply infiltrated the myometrium. The tumor was very necrotizing. There were more than 50 mitoses per 10 fields at high magnification. The isthmus was invaded by the tumor. The diagnosis of undifferentiated uterine sarcoma was confirmed by immunohistochemistry. The tumor shows negativity for the following markers: CKAE1/AE3, h-caldesmon, α-SMA, progesterone receptors, desmin, CD 10, alpha foeto-protein, CD 3 and CD 20.