[946] SALL4 Is a Novel Sensitive and Specific Marker for Ovarian Primitive Germ Cell Tumors and Distinguishes Yolk Sac Tumor from Clear Cell Carcinoma

D Cao, S Guo, RW Allan, AM West, K Molberg, Y Peng. Washington University in Saint Louis, Saint Louis, MO; Xijing Hospital, Xian, Shanxi, China; University of Florida, Gainesville, FL; UT-Southwestern Medical Center, Dallas, TX

Background: Ovarian yolk sac tumor (YST) is rare but highly malignant. Morphologically YST can closely mimic clear cell carcinoma (CCC) or vice versa. EMA, CK7, CD15, glypican-3 and AFP have been used to distinguish YST from OCC but they lack high sensitivity and/or specificity. The goal of this study is to investigate the diagnostic utility of a novel stem cell marker SALL4 in ovarian YST and other primitive GCTs and its utility to distinguish YST from CCC.
Design: Eighty three ovarian GCTs were retrieved including 24 YST, 18 dysgerminomas, 6 gonadoblastomas (GBs), 2 embryonal carcinomas (ECs), 21 teratomas (10 mature, 11 immature), 7 primary carcinoid tumors, 2 strumal carcinoid tumors, and 3 struma ovarii. To testify SALL4 specificity in ovarian tumors, we also stained 160 primary non-GCTs including 45 CCCs, 20 endometrioid carcinomas, 20 serous carcinomas (CAs) (16 high grade and 4 low grade) , 23 mucinous CAs, 2 transitional cell CAs, 2 hypercalcemic type small cell CAs, 10 Sertoli-leydig cell tumors, 8 steroid cell tumors, 10 adult granulosa cell tumors, 8 juvenile granulosa cell tumors, 6 fibrothecomas, and 6 benign Brenner tumors. Unstained slides generated from 1 to 2 paraffin embedded tissue blocks per case were stained with a SALL4 monoclonal antibody. Only nuclear staining was counted as positive. The staining intensity was scored as weak or strong. The percentage of tumor cells stained was scored semiquantitatively as: 0 (no tumor cell staining), 1+ (<=30% cells), 2+ (31-60%), 3+ (61-90%), and 4+ (>90%).
Results: All 24 YSTs, 18 dysgerminomas, and 2 ECs showed 4+ (>90% tumor cells) strong SALL4 staining. The neoplastic germ cells in GBs showed 4+ strong SALL4 staining in 6/6 cases but the intermingled sex-cord type cells were negative. Eight of 11 immature teratomas showed weak to strong 1+ staining in immature elements and some teratomatous glands. Other germ cell tumors were all negative for SALL4. Among the non-GCTs, only 3 CCCs showed 1+ (less than 1% tumor cells) weak SALL4 staining. The remaining non-GCTs all were negative for SALL4.
Conclusions: SALL4 is a novel sensitive and specific marker for ovarian YST, dysgerminomas, GB, and EC. SALL4 distinguishes yolk sac tumor from CCC.
Category: Gynecologic

Wednesday, March 11, 2009 9:30 AM

Poster Session V # 164, Wednesday Morning