[1132] IMP2, a Promising Biomarker Identifies Precursor of Endometrioid Carcinoma

Y Liu, L Zhang, K Dresser, D Lu. UMass Memorial Medical Center, University of Massachusetts, Worcester, MA

Background: Endometrioid carcinoma is preceded by precursors, of which the diagnosis is difficult and inconsistent. Biomarker, PTEN, has been proven of diagnostic utility. Here we present a new biomarker IMP2, an insulin-like growth factor II mRNA-binding protein. We demonstrate that loss of IMP2 expression can specifically identify the precursors of endometrioid carcinoma.
Design: 308 cases are selected from University of Massachusetts between 1999 and 2002; benign endometrium (n=92), simple or complex hyperplasia without atypia (n=51), complex hyperplasia with atypia (n=83), and low grade endometrioid carcinoma (n=82); including endometrial curettage/biopsy (n=144) and hysterectomy (n=178). H&E and IMP2 immunohistochemical stains are performed on consecutive tissue sections following routine method. Positive staining is defined as dark brown cytoplasmic staining.

The glandular epithelium in both benign endometrium and complex hyperplasia without atypia have IMP2 staining (Figure 1A, 1B). The stroma has no staining, which provides a clean background. Complete loss of IMP2 expression is observed in complex hyperplasia with atypia alone (Figure 1C) or that adjacent to carcinoma (Figure 1D). The IMP2 negative gland is clearly demarcated from the adjacent positive gland (Figure 1 E). Low grade endometrioid carcinomas demonstrate loss of IMP2 expression (Figure 1F).

Figure 2 shows IMP2 is positive in 100% of benign endometrium and 98% of simple or complex hyperplasia cases, but only 5% of complex hyperplasia with atypia and 10% of the low grade carcinoma cases.
Conclusions: Atypical hyperplasia and low grade endometrioid adenocarcinoma, in a sharp contrast to benign emdometrium, showed a completely and persistent loss IMP2 expression. Therefore, IMP2 is a promising specific and sensitive marker for precursors of endometrioid adenocarcinoma, especially in the diagnostic challenging cases.
Category: Gynecologic & Obstetrics

Wednesday, March 24, 2010 9:30 AM

Poster Session V # 133, Wednesday Morning


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