[840] Somatic-Type Cancers in Patients with Testicular Germ Cell Tumors: Relationship to Yolk Sac Tumor and Utility of New Markers

Cristina D Cole, Thomas M Ulbright. Indiana University School of Medicine, Indianapolis, IN

Background: Patients with testicular germ cell tumors (TGCT) occasionally develop neoplasms that resemble tumors of somatic lineage. When these are found in metastatic sites it may be difficult to distinguish them from a newly developed tumor. We investigated the utility of several immunohistochemical (IHC) stains, especially SALL4, a marker that recognizes GCTs with high specificity and sensitivity, in the recognition of these "somatic-type germ cell-derived cancers” (STGCDC).
Design: We selected 38 cases of STGCDCs of various types from our files from 1990-2010. The patients were young men (mean, 37.4 years; range, 18-57) with known TGCTs who had excision of STGCDCs from typical metastatic sites after chemotherapy. The H&E slides were reviewed and the tumors initially classified based on morphology and previously performed IHC stains. Immunostaining for SALL4 was performed in all cases and scored by adding intensity (0-3) and extent (0-3). In selected cases, stains for glypican 3 (GPC3), AFP, CK7, AE1/3 and EMA were also performed. Based on the results of the latter, 6 previously diagnosed sarcomas were reclassified as sarcomatoid yolk sac tumors (YST), 4 adenocarcinomas as glandular YSTs, and 1 clear cell carcinoma as solid YST.
Results: The results are summarized in the following table (# positive cases / # total stained cases), with the mean staining scores for SALL4 positive cases provided in parentheses.

Adenocarcinoma / Carcinoma, NOS (n=15)8/15 (3.9)1/30/61/44/62/2
Low-grade mucinous neoplasm (n=3) / Mucinous carcinoma (n=2)1/5 (3.0)0/30/31/33/3 
Glandular yolk sac tumor* (n=4)3/4 (5.3)3/32/30/31/3 
Solid yolk sac tumor† (n=1)1/1 (6.0)1/10/11/11/1 
Sarcomatoid yolk sac tumor‡ (n=6)5/6 (4.6)5/50/60/50/36/6
Teratoma with intraepithelial carcinoma (n=1)1/1 (5.0)     
Myxoid/myofibroblastic sarcoma (n=1)0/10/10/10/10/10/1
Embryonal rhabdomyosarcoma (n=4)1/4 (3.0)     
Malignant glioma (n=1)0/1     
Total (n=38)20/38     
*Originally diagnosed as adenocarcinoma; †Originally diagnosed as clear cell carcinoma; ‡Originally diagnosed as sarcoma

Conclusions: SALL4 is a helpful marker in the recognition of epithelial STGCDCs but not for STGCDCs showing specific forms of sarcomatous differentiation. Application of newly available markers, but not AFP, clarifies that a significant subset of apparent somatic-type cancers in patients with TGCTs are unusual, chemoresistant forms of YST. SALL4 shows particular positivity in these cases, with comparatively higher mean staining scores.
Category: Genitourinary (including renal tumors)

Wednesday, March 6, 2013 9:30 AM

Poster Session V # 154, Wednesday Morning


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