[905] Evaluation of LIN28 as a Pan-Germ Cell Tumor Marker Using Germ Cell Tumor Tissue Microarrays

Arivarasan Karunamurthy, Somak Roy, Sarangarajan Ranganathan, Anil Parwani. University of Pittsburgh Medical Center, Pittsburgh, PA

Background: LIN28 a predominantly RNA-binding cytoplasmic protein, plays important role in gene expression regulation and maintainence of the pluripotency of embryonic stem cells. Recent studies have shown the role of LIN28 in malignant transformation of germ cells in animals. Our aim was to evaluate the diagnostic utility of LIN28 expression in testicular germ cell tumors (GCT).
Design: Two tissue microarrays constructed from various primary and metastatic testicular GCTs were stained with LIN28 antibody. The cytoplasmic staining was considered positive and scored as negative, weak, moderate, or strong staining.
Results: A total of 69 GCTs were obtained of which 52 (75%) were primary testicular GCTs (35 seminomas; 14 embryonal carcinomas; 3 yolk sac tumors; 6 teratomas and 20 intratubular germ cell neoplasias) and 17(25%) were metastatic testicular germ cell tumors containing (1 seminomas; 5 embryonal carcinomas; 3 yolk sac tumors; 8 teratomas and 1 choriocarcinoma) along with 19 normal testicular tissue cores adjacent to the above tumors. Strong LIN28 staining is observed in 30 (83%) seminomas, 25 (100%) embryonal and yolk sac tumors, 19 (95%) ITGCNs and 1 (100%) choriocarcinoma without any significant difference between primary and metastatic. Teratomas showed either negative (50%) or weak (50%) staining due to presence of mature epithelial or mesenchymal tissues. Normal testicular germ cells showed mostly (95%) weak staining.

Table:1 Immunohistochemical staining of LIN28 in 52 primary testicular GCTs and 17 metastatic testicular GCTs.

	Primary or Metastatic	Negative	Weak Staining	Moderate staining	Strong Staining
Specimen Category
Seminoma (n=36	Primary	0	0	6 (17%)	29 (83%)
	Metastatic	0	0	0	1 (0%)
Embryonal Carcinoma(n=19	Primary	0	0	0	14 (74%)
	Metastatic	0	0	0	5 (26%)
Yolk sac tumor(n=6)	Primary	0	0	0	3 (50%)
	Metastatic	0	0	0	3 (50%)
Teratoma(n=14)	Primary	3 (25%)	1 (8%)	0	0
	Metastatic	3 (25%)	5 (42%)	0	0
Choriocarcinoma(n=1)	Primary	0	0	0	0
	Metastatic	0	0	0	1 (100%)
ITGCN(n=19)		0	0	1 (5%)	19 (95%)
Normal testicular tissue (n=19)		1 (5%)	18 (95%)	0	0

Conclusions: LIN28 cytoplasmic expression by immunohistochemistry increases from complete negativity in mature epithelial cells, weak staining in normal testicular germ cells to moderate to strong staining in neoplastic germ cells. LIN28 can be used as highly sensitive marker to diagnose both primary and metastatic testicular germ cell tumors, particularly intratubular germ cell neoplasias, classical seminomas, embryonal carcinomas, yolk sac tumors and choriocarcinomas. It could also be used in identifying the mixed germ cell components within teratomas.
Category: Genitourinary (including renal tumors)

Monday, March 19, 2012 1:00 PM

Poster Session II # 132, Monday Afternoon