[962] CDX2 Is Superior to Alpha-Fetoprotein in Yolk Sac Tumors (YST) Both in Adult and Pediatric Patients: Study with Emphasis on Morphologic Patterns

Golnaz Naderkhani, Alfredo Pinto, Kiril Trpkov, Tarek Bismar, Asli Yilmaz. Calgary Laboratory Services and University of Calgary, Calgary, AB, Canada

Background: YST can be diagnostically challenging due to its diverse morphologic patterns. Alpha-fetoprotein (AFP), a traditional YST marker, has also some limitations. CDX2, an antibody often used in intestinal adenocarcinomas, has recently been reported to be positive in adult testicular and ovarian YST, but it has not been studied in pediatric YST. We studied CDX2 expression both in adult testicular and pediatric YST.
Design: We compared the expression of CDX2 and AFP in 28 GCT: 22 adult testicular YST and 6 pure pediatric testicular (1) and extratesticular (5) YST. In adults, YST component ranged from 10% to 100%. The YST patterns were as follows: microcystic (75%), glandular (39%), myxomatous (36%), papillary (32%), macrocystic (25%), endodermal sinus (21%), solid (21%),and polyvesicular vittelline (11%). We used as negative controls, the non-YST components of mixed GCT and 6 additional pure GCT (4 seminoma, 2 embryonal), all confirmed by positive OCT 3/4. Extent of staining was scored as 0 (<5%), 1+ (5%-10%), 2+ (11%-50%) and 3+ (>50%). Staining intensity was graded from 0-3+.
Results: CDX2 was positive in 100% (6/6) of pediatric YST: No cases 0 or 1+, 3 cases each with 2+ and 3+. Mean intensity was 3. AFP stained 83% (5/6) pediatric YST: 1 with 0, 1 with 1+, 3 with 2+ and 1 with 3+. Mean intensity was 2.6. In adults, 91% (20/22), expressed CDX2: 2 (9%) with 0+, 4 (18%) with 1+, 8 (36%) with 2+ and 8 (36%) with 3+ staining. The mean intensity of CDX2 staining was 2.5. In adult YST, AFP stained 95% (21/22) cases: 1 (5%) with 0+, 6 (27%) with 1+, 11 (50%) with 2+ and 4 (18%) with 3+ staining. The mean intensity of AFP staining in the adult YST component was 2.5. Regarding the expression of CDX2 vs AFP in different YST patterns, CDX2 was superior in myxomatous (70% vs 0%), papillary (89% vs 55%) and macrocystic (71% vs 14%) patterns. Both antibodies were comparable in microcystic (90% vs 95%), endodermal sinus (66% vs 66%), polyvesicular (66% vs 33%) and solid (66% vs 66%) patterns. Seminomas and embryonal carcinomas were uniformly negative for both antibodies. CDX2 was expressed only in intestinal component of teratomas.
Conclusions: We found that CDX2 is an excellent marker for pediatric YST, which was not reported previously. We also confirmed that CDX2 is a useful marker identifying YST component in adult GCT. CDX2 is superior to AFP in detecting the commonly overlooked YST patterns such as myxomatous papillary and macrocystic. In contrast to AFP, CDX2 has distinct nuclear expression without background staining.
Category: Genitourinary (including renal tumors)

Monday, March 19, 2012 1:00 PM

Poster Session II # 135, Monday Afternoon


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