[1043] Immunohistochemical (IHC) Characterization of Sex Cord Stromal Tumors

O Moshkin, S Nofech-Mozes, MA Khalifa, N Ismiil, V Dube, RS Saad, Z Ghorab. University of Toronto, Toronto, Canada; Sunnybrook Health Sciences Centre, Toronto, Canada

Background: Sex cord stromal tumors (SCST) account for 8% of all primary ovarian tumors. Despite their rarity, SCST are often considered in the differential diagnosis of ovarian neoplasms and metastatic tumors since their morphologic features overlap with various epithelial and germ cell tumors. The aim of this study is to characterize the level and pattern of expression of an updated panel of immunohistochemical markers that will assist in their differential diagnosis. Special emphasis is given to the extent of EGFR expression since it represents a potential marker for targeted therapy with monoclonal antibodies.
Design: In-house ovarian and testicular SCST cases accessioned between 1999-2008 were retrieved from the archive of Sunnybrook Health Sciences Centre. Two gynecologic pathologists reviewed the cases using the WHO classification and studied the IHC profile using a panel of antibodies against: inhibin, calretinin, CD56, CD99, D2-40, LMWK (cam 5.2), CD10, Melan A, EMA and EGFR. Immunostaining was recorded semiquantitatively.
Results: We identified 67 SCST (63 ovarian and 4 testicular): 37 adult granulosa cell tumors, 9 fibrothecomas, 8 Sertoli-Leydig cell tumors, 4 sex cord stromal tumors with anular tubules, 3 sclerosing stromal tumors, 3 unclassified, 2 steroid cell tumors, and 1 gynandroblastoma. The following proportions of positive cases were demonstrated: inhibin 60/67 (88.5)%, calretinin 58/67 (86.5)%, CD56 56/67(83.5%), CD99 31/67 (46.2)% predominantly in <50% of the tumor, D2-40 28/67 (41.7%) (cytoplasmic granular pattern), LMWK 15/67 (22.3%) including 4 cases with positivity in >50% of the tumor, CD10 5/62 (7.4%), Melan A 5/62 (7.4%), and EMA 1/67 (1.1%), in <25% of the tumor. Interestingly, 74.6% of the cases expressed EGFR (membranous pattern), in 44 cases >50% of the tumor was positive.
Conclusions: Our IHC results (inhibin, calretinin, CD56, and CD99) confirm earlier reports of the sex cord lineage of these tumors. However, attention should be made when LMWK is used as part of a panel differentiating SCST from carcinomas since a significant proportion of SCST are positive. Our results provide a rationale for considering targeted therapy against EGFR in clinically aggressive tumors as it is expressed in a high proportion of cases.
Category: Gynecologic

Monday, March 9, 2009 9:30 AM

Poster Session I Stowell-Orbison/Autopsy Award # 160, Monday Morning