[1472] IMP3 Expression Can Distinguish Hepatocellular Carcinoma from Hepatocellular Adenoma

DG Wagner, Q Yang, LA McMahon, BO Spaulding, HL Wang, H Xu. University of Rochester Medical Center, Rochester; Dako North America, Carpinteria, Carpinteria; Cedars-Sinai Medical Center, Los Angeles

Background: Insulin growth factor (IGF) messenger RNA binding protein 3 (IMP3), also known as K homology domain containing protein overexpressed in cancer and L523S, is predominantly expressed in embryogenesis. In recent years, IMP3 expression has been identified in multiple malignant neoplasms including hepatocellular carcinoma (HCC) (Jeng YM, et al. Hepatology, in press). The study by Jeng YM et al also indicated that IMP3 plays an important role in tumor invasion and metastasis and is a strong prognostic factor for patients with HCC. It is often difficult to segregate hepatocellular adenoma (HCA) from HCC when HCC is well-differentiated and/or limited tissue from a needle biopsy is examined. The aim of this study was to determine if immunohistochemical detection of IMP3 serves as a useful diagnostic tool in the distinction between these two hepatocellular neoplasms.
Design: Fifty-two surgical resected or biopsied specimens of well- to moderately- differentiated HCC (resection, n=16; needle, n=3) and HCA (resection, n=31; needle, n=2) were obtained from University of Rochester and Cedars-Sinai Medical Centers. Immunohistochemistry was performed using a monoclonal antibody against IMP3 (Dako). Cytoplasmic staining was considered positive. The percentage of positively stained tumor cells was recorded and the staining intensity was graded as weak, moderate, or strong.
Results: Immunohistochemical studies showed that 12 of 19 well- to moderately- differentiated HCCs (63%) were moderately to strongly positive for IMP3. Among them, 9, 1 and 2 cases showed 5-10%, 20% and >90% of tumor cells positively stained for IMP3, respectively. Interestingly, IMP3 protein was predominantly expressed in tumor cells at the periphery of the tumors. In contrast, no IMP3 expression was detected in any of 33 HCAs or non-neoplastic hepatic tissues.
Conclusions: A large proportion of HCCs expressed IMP3 with a predominant staining at the periphery of the tumors, but HCAs and non-neoplastic hepatic tissues did not. These findings indicate immunohistochemical detection of IMP3 expression can serve as an additional diagnostic tool in segregating well differentiated HCC from HCA or non-neoplastic hepatic tissues, in particular when limited material from a needle biopsy is evaluated.
Category: Liver & Pancreas

Tuesday, March 10, 2009 9:30 AM

Poster Session III # 167, Tuesday Morning