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A 75-year-old female presents to the doctor with a chief complaint of vaginal spotting. She has been
post-menopausal for 25 years and does not take hormones. An ultrasound is performed, and 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?
A. Endolymphatic stromal myosis
B. Endometrial carcinoma
C. Endometrial stromal sarcoma
D. Leiomyosarcoma
E. Malignant mixed müllerian tumor
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The correct answer is E. Malignant mixed müllerian tumor is a tumor with 2 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 post-menopausal bleeding. The stromal component can contain metaplastic
components such as cartilage and bone. Interestingly, usually only the epithelial component
metastasizes.
Endolymphatic stromal myosis (choice A) 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 half of patients and metastasis occurs in 15%.
There is no epithelial component, so this is an incorrect choice.
Endometrial carcinoma (choice B) 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 (choice C) is a true sarcoma arising from the endometrial stroma
that infiltrates the myometrium and invades vessels. There is no epithelial component.
Leiomyosarcoma (choice D) 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.
