[1701] Utility of Bile Salt Export Pump Transporter Immunohistochemistry Compared to Other Hepatocellular Markers for the Diagnosis of Hepatocellular Carcinoma

Thuy Nguyen, Daniel Phillips, Sanjay Kakar. UCSF, San Francisco, CA

Background: Bile salt export pump transporter (BSEP) is encoded by the ABCB11 gene and is expressed on the apical side of the bile canalicular membrane in hepatocytes. The role of BSEP for the diagnosis of hepatocellular carcinoma (HCC) has been suggested but not explored in detail.
Design: Immunohistochemistry for BSEP was performed on 71 HCC. The cases were stratified into well differentiated (WD, n=13), moderately differentiated (MD, n=35) and poorly differentiated (PD, n=23) HCC based on WHO criteria. More than one differentiation pattern was seen in 12 cases; these were scored separately yielding 83 observations. Canalicular staining pattern with BSEP was considered positive. The staining intensity was recorded on a scale of 0-3; 2+ or 3+ staining in >5% of tumor cells was considered positive. The results were compared with other hepatocellular markers that had been previously done in the same cases: Hep Par 1 (Hep), polyclonal CEA (pCEA), glypican-3 (GPC) and arginase-1 (Arg).
Results: When staining of >5% of tumor was considered positive, BSEP had a sensitivity of 76% (92% in WD-HCC, 95% in MD-HCC, and 45% in PD-HCC). When staining of >50% of tumor was considered positive, the overall sensitivity of BSEP decreased to 47% (69% in WD-HCC, 72% in MD-HC, and 6% in PD-HCC). Membrane staining with BSEP was seen in 8 (9.6%) HCCs, which obscured the canalicular staining pattern. BSEP was similar to Arg, Hep and pCEA in WD and MD HCC. For PD HCC, the sensitivity was lower compared to GPC and Arg. The addition of BSEP to other hepatocellular markers did not lead to increase in sensitivity for any differentiation.

Table 1
Numbers a/b reflect percentages; a-positivity in >5% of tumor, b-positivity in >50% of tumor

Table 2
WD HCC100/100100/69100/100100/85
MD HCC100/97100/95100/8597/90
PD HCC97/8197/7468/3271/19
Numbers a/b reflect percentages; a-positivity in >5% of tumor, b-positivity in >50% of tumor

Conclusions: BSEP can be used as a marker for hepatocellular differentiation and shows a crisp canalicular pattern of staining. It has high sensitivity in WD and MD HCC, which is comparable to Arg, Hep and pCEA. BSEP immunoreactivity is seen in less than half of the PD HCC, which is significantly lower compared to Arg and GPC. Although BSEP appears to have good overall sensitivity, its role in establishing hepatocellular differentiation is limited when added to a panel of Hep, GPC and Arg.
Category: Liver

Wednesday, March 6, 2013 1:00 PM

Poster Session VI # 121, Wednesday Afternoon


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