[370] Arginase-1 Is a More Sensitive Marker of Hepatic Differentiation Than HepPar-1 in Fine Needle Aspiration Biopsy Specimens.

Mika Fujiwara, Reetesh K Pai. Stanford University, CA

Background: Distinguishing hepatocellular carcinoma (HCC) from adenocarcinoma in fine needle aspiration biopsies (FNAB) is often diagnostically challenging. Arginase-1 was recently described as a marker of hepatic differentiation in surgical resection specimens. We compared the reactivities of Arginase-1 and HepPar-1 in FNAB of HCC and adenocarcinoma involving the liver.
Design: Seventy-four FNAB including 31 primary or metastatic HCC (27 well/moderately differentiated and 4 poorly differentiated) and 43 adenocarcinomas involving the liver were evaluated. Immunohistochemical staining for Arginase-1 (polyclonal, Sigma-Aldrich, 1:200) and HepPar-1 (clone OCH1E5, Dako, 1:200) was performed on formalin-fixed cell block material. Only cytoplasmic staining was scored as positive staining for both Arginase-1 and HepPar-1. Staining intensity (weak versus strong) and extent (focal, <10% versus diffuse, >10%) were scored.
Results: Arginase-1 was more sensitive (27/31, 87%) than HepPar-1 (25/31, 81%) for HCC (Table 1). Arginase-1 more often demonstrated strong (26/27, 96%) and diffuse (18/27, 67%) staining in HCC compared with HepPar-1 (20/25, 80% and 14/25, 56%, respectively). Arginase-1 staining was identified in adenocarcinomas of the pancreas, breast, and colorectal origin, although reactivity was typically weak and focal. HepPar-1 demonstrated strong and diffuse reactivity in cases of gastric, pulmonary, and prostatic adenocarcinoma.

Arginase-1 and HepPar-1 in Hepatocellular Carcinoma and Adenocarcinoma in FNAB
Tumor TypeArginase-1 Positive (%)HepPar-1 Positive (%)
Well/moderately differentiated HCC25/27 (93)24/27 (89)
Poorly Differentiated HCC2/4 (50)1/4 (25)
Colorectal and Anal carcinoma2/16 (13)0/16 (0)
Breast adenocarcinoma1/12 (8)0/12 (0)
Pancreatic adenocarcinoma3/7 (43)0/7 (0)
Pulmonary adenocarcinoma0/3 (0)1/3 (33)
Prostatic adenocarcinoma0/2 (0)1/2 (50)
Gastric adenocarcinoma0/1 (0)1/1 (100)
Intrahepatic cholangiocarcinoma0/1 (0)0/1 (0)
Uterine carcinoma0/1 (0)0/1 (0)

Conclusions: Arginase-1 is a more sensitive marker of hepatic differentiation than HepPar-1 in FNAB specimens. In addition, Arginase-1 exhibits stronger and more diffuse positive staining in HCC than HepPar-1 making interpretation easier in limited FNAB samples. Arginase-1 is not entirely specific for hepatic differentiation, as focal, weak immunoreactivity can be identified adenocarcinomas of pancreatic, breast, and colorectal origin.
Category: Cytopathology

Tuesday, March 1, 2011 9:30 AM

Poster Session III # 56, Tuesday Morning


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