What is a Uterine Sarcoma?

A type of cancerous tumor in the uterus, a uterine sarcoma arises in connective tissue or smooth muscle, as opposed to the endometrium or uterine lining. Uterine sarcomas are relatively rare, comprising only about four percent of uterine malignancies; most are endometrial sarcomas. A uterine sarcoma usually manifests after menopause. Treatment usually takes the form of surgical removal, radiation, chemotherapy, and, or, hormone therapy.

Anatomically, the uterus consists of three layers. The innermost is the endometrium, a lining of columnar epithelial tissue that rests on a layer of connective tissue, the stroma. The next layer is the myometrium, made of smooth muscle, the type of muscle tissue in all the body's organs except the heart. Finally, the uterus is enclosed by the perimetrium, a serous membrane that also consists of a layer of epithelial tissue and a layer of connective tissue. Uterine sarcoma affects either the stroma or the myometrium.

There are three major types of uterine sarcoma, classified according to the tissue from which they arise, though some uterine sarcomas do not fit into one of these groups. Endometrial stromal sarcomas arise from the stroma of the endometrium, which lies between the endometrium and the smooth muscle. Uterine leiomyosarcomas arise from the smooth muscle, and uterine carcinosarcomas, also called malignant mixed Müllerian tumors, contain cancerous cells of both epithelial and connective tissue origin. Uterine carcinosarcomas are further subdivided into two types: homologous, which contain only tissue types found in the uterus, and heterologous, which contain other tissue types including bone, cartilage, or skeletal muscle.

Symptoms of a uterine sarcoma include pain and pressure in the pelvis, abnormal vaginal discharge including post-menopausal or otherwise unusual bleeding, and the swelling of a non-pregnant uterus. Diagnosis often begins with imaging techniques such as ultrasound, computed tomography (CT), or magnetic resonance imaging (MRI), but it must be confirmed through microscopic inspection of the tumor. If possible, this inspection can be performed through hysteroscopy, biopsy, or dilation and curettage (D&C). In biopsy, a small portion of the tumor is removed for examination, usually through a needle. Hysteroscopy uses an endoscope, a tube with a light and lens system, to observe the inside of the uterus. In dilation and curettage, the uterus opening is dilated, or widened, and a tool is used to scrape out cells for examination.

Prognosis for uterine sarcoma is usually not very good. The preferred treatment is hysterectomy, in which the entire uterus is removed. Radiation, chemotherapy, and hormone therapy are other available treatments if surgery is not possible for some reason.