Case 18

A 45-year-old female with a large uterine mass.

What's the diagnosis by morphology?

A: Epitheloid leiomyosarcoma

B: FIGO 3 endometrioid endometrial carcinoma

C: High grade endometrial stromal sarcoma

D: Dedifferentiated carcinoma

F: Undifferentiated carcinoma

Answer

Although in real life, a panel of stains will be performed and this case is a endometrial adenocarcinoma, de-differentiated type. Tumor is predominantly (>95%) composed of an undifferentiated carcinomas with sheets of small to intermediate-sized, discohesive cells of relatively uniform size, as well as foci of a gland forming endometrioid carcinoma. Immunohistochemical studies show a differential pattern of staining between these two components with the glandular foci being strongly positive for pankeratin, E-cadherin, and PAX-8 while the dedifferentiated area showing patchy positivity for pankeratin and PAX-8 and aberrant pattern of expression for E-cadherin (loss). Both histotypes demonstrate loss of expression of PTEN and PAX-2, normal expression of betacatenin, and wild type positivity for p53. Undifferentiated carcinoma will not have the well-differentiated areas in the last picture. FIGO3 endometorid carcinoma will typically retain PAX8 and keratin with normal E-cadherin.

Case credit: UCSD Pathology

Author: Wangpan Jackson Shi, MD