Section: USMLE

17) A 75-year-old woman presents to the physician with a chief complaint of vaginal spotting. She has been postmenopausal for 25 years and does not take hormones. An ultrasound shows a mass in the uterine fundus. A hysterectomy is performed, and pathologic examination of the removed uterus reveals a malignant tumor of the endometrial glands and stroma. Which of the following is the most likely diagnosis?

1. Endolymphatic stromal myosis
2. Endometrial carcinoma
3. Endometrial stromal sarcoma
4. Leiomyosarcoma
5. Malignant mixed mullerian tumor

Malignant mixed mullerian tumor is a tumor with two components, stromal and epithelial (endometrial glands), both of which are malignant. This is a rare and highly aggressive tumor that has a 25% 5-year survival rate. It usually affects older patients and presents with postmenopausal bleeding. The stromal component can contain metaplastic components such as cartilage and bone. Interestingly, usually only the epithelial component metastasizes.

Endolymphatic stromal myosis is a type of endometrial stromal tumor of intermediate malignancy. It appears as small pieces of stroma between myometrial bundles that infiltrate lymph channels. Patients may have pain or bleeding, or may be asymptomatic. Recurrences happen late in the course of the disease (years) in 50% of patients, and metastasis occurs in 15%. There is no epithelial component, so this is an incorrect choice.

Endometrial carcinoma is a malignancy of the epithelial glandular component of the endometrium. Abnormal bleeding is the usual presentation. High estrogen states cause this tissue to proliferate. There is no stromal component of this tumor, so this is an incorrect choice.

Endometrial stromal sarcoma is a true sarcoma arising from the endometrial stroma that infiltrates the myometrium and invades vessels. There is no epithelial component.

Leiomyosarcoma is a true sarcoma arising from the uterine smooth muscle. It commonly has satellite lesions within the uterus. Leiomyosarcomas usually recur after removal; survival is greater with well-differentiated lesions. Poorly differentiated lesions have a 10% to 15% 5-year survival rate. Distant metastasis is via blood vessels. There is no epithelial component.