Coordinate patterns of estrogen receptor, progesterone receptor, and Wilms tumor 1 expression in the histopathologic distinction of ovarian from endometrial serous adenocarcinomas

The purpose of this study is to assess whether composite or coordinate immunoexpression patterns of estrogen receptor (ER), progesterone receptor (PR), and Wilms tumor 1 (WT1) gene can significantly distinguish between endometrial serous carcinoma (ESC) and ovarian serous carcinoma (OSC). Immunohistochemical analyses were performed on whole tissue sections from 22 uterus-confined ESCs and on a tissue microarray of 140 high-grade, pan-stage OSCs, using antibodies to ER, PR, and WT-1. Estrogen receptor, PR, and WT1 expressions were present in 37%, 49%, and 81% of OSC, respectively, but these markers were also present in 18%, 27%, and 36% of ESC. The ER+/PR+/WT1+ coordinate profile was identified in 33.6% of OSC but in none of ESC (P =.0006), resulting in a calculated sensitivity and specificity of this profile for OSC of 33.6% and 100%, respectively. By contrast, the ER-/PR-/WT1- coordinate profile was identified in 41% of ESC but in only 6.4% of OSC (P =.0001), resulting in a calculated sensitivity and specificity of this profile for ESC of 50% and 94%. In summary, in the differential diagnosis between OSC and ESC, positivity for all 3 markers favors an extrauterine origin, whereas negativity for all 3 markers is supportive of an endometrial origin. The use of single markers for this purpose is not recommended, as each lacks optimal discriminatory power. Coordinate profiles, in general, have a high specificity but low sensitivity in this differential diagnosis.