[1423] Expression of Glypican-3 in Embryonal Sarcoma (ES) and Mesenchymal Hamartoma (MH) of the Liver: A Potential Diagnostic Pitfall

M Levy, D Dhall, J Zhang, L Miles, J Misdraji, LM Yerian, H Xu, CE Aguilar, HL Wang. Cedars-Sinai Medical Center, Los Angeles; Mayo Clinic, Rochester; Cincinnati Children's Hospital, Cincinnati; MGH/Harvard Medical School, Boston; Cleveland Clinic, Cleveland; University of Rochester Medical Center, Rochester

Background: Glypican-3 (GPC3) is an oncofetal protein that has recently been demonstrated to be a useful diagnostic immunomarker for hepatocellular carcinoma and hepatoblastoma. Its expression in mesenchymal tumors of the liver, particularly ES and MH, has not been investigated.
Design: A total of 16 ESs and 12 MHs were retrieved from authors' institutions and stained for GPC3 using antibody 1G12. A case was considered negative if <1% of the cells of interest exhibited immunoreactivity. Positive staining was graded as weak, intermediate or strong, and as focal if 1-50% of the cells stained or diffuse if >50% of the cells stained.
Results: The ages of patients with ES ranged from 6-87 years (mean: 37.2 years; median: 23.5 years). Nine were male and 7 were female. The tumor sizes ranged from 2.4-20 cm (mean: 10.5 cm). The ages of patients with MH ranged from 0.2-72 years (mean: 12.8 years; median: 1.3 years). Six were male and 6 were female. The tumor sizes ranged from 2.4-34 cm (mean: 10.8 cm). Intermediate to strong cytoplasmic staining for GPC3 was observed in 8 (50%) ESs, of which 2 cases exhibited diffuse immunoreactivity and the remaining 6 showed focal positivity. The patients with GPC3-postive ESs tended to be younger (mean age: 29.9 years) than those with negative tumors (mean age: 44.5 years), although the difference was not statistically significant (P=0.17). Five MHs also exhibited GPC3 immunoreactivity (41.7%; 3 focal, 2 diffuse). However, positive staining was primarily seen in entrapped hepatocytes with a cytoplasmic/canalicular staining pattern; in only 2 cases was weak and focal immunoreactivity also observed in mesenchymal component. Interestingly, all the patients with positive staining were younger than 1.5 years old.
Conclusions: GPC3 is expressed in a subset of ESs and MHs of the liver. Caution should be exercised when evaluating a GPC3-expressing hepatic neoplasm, particularly in a needle biopsy, when the differential diagnosis includes poorly differentiated hepatocellular carcinoma and hepatoblastoma. The observed GPC3 staining patterns may be also helpful in the rare instance of ES arising in MH since the former appears to be more likely positive for GPC3.
Category: Liver & Pancreas

Tuesday, March 10, 2009 9:30 AM

Poster Session III # 174, Tuesday Morning