[1201] PAX-8 and ER in Mucinous Tumors in the Ovary: Are They Useful in Distinguishing Primary from Metastasis?

Ramya P Masand, Anais Malpica, Preetha Ramalingam. Baylor College of Medicine, Houston, TX; UT MD Anderson Cancer Center, Houston, TX

Background: PAX-8 is expressed in tumors of the Mullerian system, kidney, and thyroid. Studies have shown that PAX-8 can be useful in differentiating primary ovarian mucinous tumors (OV-MT) from metastatic tumors (mets) of gastrointestinal and pancreatic origin. However, the expression of this marker in OV-MT has been reported to be variable, ranging from 8.3% to 65%. Also, ER expression in OV-MT has been reported to vary from 0% to 70%. In this study, we present our experience with the expression of these markers in OV-MT and in mets.
Design: 13 mucinous cystadenomas (Mcyst), 12 mucinous tumors of low malignant potential, intestinal type (MLMPi), 2 mucinous tumors of low malignant potential, endocervical type (MLMPe), 8 primary ovarian mucinous carcinomas (MCa) and 4 cases of mets (1 appendiceal, 1 pancreatic and 2 colonic carcinomas) to the ovary were retrieved from our files. PAX-8 and ER were performed. Nuclear staining was assessed semiquantitatively: 0 (negative), 1+ (<5%), 2+ (6-25%), 3+ (26-50%), 4+ (51-75%), and 5+ (>76%).
Results: PAX-8 was positive in 11/13 Mcyst (85 %), 10/12 MLMPi (83 %), 2/2 MLMPe (100 %) and 5/8 MCa (63 %). In Mcyst, 3 cases (23 %) were 1+, 1 (8 %) was 2+, 3 (23 %) were 3+, 1 (8 %) was 4+, and 3 (23 %) were 5+. In MLMPi, 1 case (8 %) was 1+, 3 (25 %) were 2+, 2 (17 %) were 4+, and 4 (33 %) were 5+. In MLMPe, 2 cases were 5+ (100%). In MCa, 1 case (13 %) was 1+, 1 (13 %) was 2+, and 3 (38 %) were 5+. Mets were negative for PAX-8. ER was positive in 2/13 Mcyst (16 %), 1/12 MLMPi (8 %), 2/2 MLMPe (100%), and 3/6 MCa (50 %). In Mcyst, 1 case (8 %) was 2+, and 1(8 %) was 5+. In MLMPi, 1 case (8 %) was 1+. In MLMPe, 2 cases (100 %) were 5+. In MCa, 2 cases (33 %) were 2+, and 1 (17 %) was 5+. Mets were negative for ER.

Table-1: Expression of PAX-8 in Mucinous Neoplasms of the Ovary
PAX-801+2+3+4+5+
Mcyst (n=13)231313
MLMPi(n=12)213-24
MLMPe(n=2)-----2
MCa (n=8)311--3




Table-2: Expression of ER in Mucinous Neoplasms of the Ovary
ER01+2+3+4+5+
Mcyst (n=13)11-1--1
MLMPi(n=12)111----
MLMPe(n=2)-----2
MCa (n=6*)3-2--1
*ER was not performed in 2 of 8 cases of MCa.


Conclusions: In this study, PAX-8 was expressed in 28 of 35 (80 %) OV-MT and negative in the mets. Mcyst and MLMP show much higher PAX-8 expression when compared to MCa. ER is positive in only 8 of 33 (24 %) OV-MT and this precludes its utility as a distinguishing marker between OV-MT and mets. In a mucinous tumor in the ovary, PAX-8 expression strongly favors an ovarian origin.
Category: Gynecologic & Obstetrics

Wednesday, March 6, 2013 9:30 AM

Poster Session V # 168, Wednesday Morning

 

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