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Background: Utilization rates of immunohistochemistry (IHC) for the diagnosis of Helicobacter pylori infection may vary by laboratory and/or pathologists. IHC for H. pylori is not performed routinely in our practice. Instead, it is used in selected cases at the pathologists' discretion (and according to their specific criteria). The purpose of this study was to determine if IHC utilization rates correlated with rates of detecting H. pylori infection., Materials and Methods: We searched our records and investigated all gastric biopsies for 1 calendar year. H. pylori diagnostic rate and IHC utilization rate was calculated for each pathologist., Results: Overall, the rate of diagnosis was 12.1% and the IHC utilization rate was 45.2%. Individual pathologists had H. pylori diagnostic rates ranging from 3.6% to 34.1% (median: 11.1%) and IHC utilization ranging from 17.1% to 95.2% (median: 42.2%). The rate of detection of H. pylori infection among pathologists showed no significant correlation with rates of IHC utilization (Pearson coefficient=0.121)., Conclusions: Increasing use of IHC is not independently associated with the diagnostic rate of infection. Ultimately, if we assume that the case mix was similar for each pathologist, it suggests that more liberal criteria to order IHC does not result in more infections diagnosed.

Introduction: Glutamine synthetase (GS), heat shock protein-70 (HSP-70), and glypican-3 (GPC-3) are markers best characterized in hepatocellular lesions, where they are useful in distinguishing hepatocellular carcinoma from dysplastic nodules. Their staining patterns in intrahepatic cholangiocarcinoma (IH-ChCa) and metastatic tumors in liver are not well described., Methods: Tissue microarrays containing 41 IH-ChCa and 24 metastatic tumors in liver were stained with commercially available antibodies to GS, HSP-70, and GPC-3. Five percent staining of tumor cells was considered positive for HSP-70 and GPC-3. For GS, 50% was the cut-off., Results: GS reactivity was present in 31 of 41 IH-ChCa (76%), with the median amount of staining being 65% of tumor cells. HSP-70 reactivity was present in 36 of 41 IH-ChCa (88%) with the median amount of staining being 75% of tumor cells. GPC-3 reactivity was absent from all IH-ChCa. Twenty-seven of 41 IH-ChCa cases were positive for both GS and HSP-70 (66%). GS reactivity was present in 17 of 24 tumors metastatic to liver (71%), with the median amount of staining being 50% of tumor cells. HSP-70 reactivity was present in 21 of 24 tumors metastatic to liver (88%) with the median amount of staining being 80% of tumor cells. GPC-3 reactivity was present in 2 of 24 tumors metastatic to liver (8%) with one showing 5% staining and the other showing 50% staining of tumor cells. Fifteen of 24 cases were positive for both GS and HSP-70 (63%), and 2 cases were positive for all 3 markers (8%)., Discussion: Of the panel of immunostains currently commonly used to distinguish hepatocellular carcinoma from dysplastic hepatocytic nodules, only GPC-3 did not react frequently with metastatic tumors and IH-ChCa, although there was staining in 2 metastatic tumors. GS and HSP-70 are typically positive in IH-ChCa and metastatic tumors. Nothing should be inferred about the histogenesis of a tumor based on positive staining with either of these 2 markers, which currently have no role in tumor of unknown origin panels.

Background: The pathologic distinction between hepatocellular carcinoma (HCC) and hepatocellular adenoma (HCA) is sometimes problematic due to histologic overlap between the 2 entities, a problem amplified on small biopsy specimens. Several recently characterized immunohistochemical markers such as glypican-3 (GPC-3), heat-shock protein-70 (HSP-70), and glutamine synthetase (GS) help distinguish dysplastic nodules from HCC. The utility of this panel in the distinction of low-grade hepatocellular carcinoma (LG-HCC) from HCA has not been fully described., Objective: To determine whether the above markers are useful in the distinction of HCCs from HCAs., Design: Tissue microarrays were constructed with 30 LG-HCCs and 18 HCAs. The arrays were stained with the above markers and analyzed with respect to amount and pattern of staining. GPC-3 and HSP-70 were considered positive when 10% of tumor cells showed immunoreactivity. GS was considered positive when 50% of tumor cells showed immunoreactivity., Results: GPC-3 was positive in 13 of 30 LG-HCCs and 0 of 18 adenomas. The sensitivity was 43% and the specificity was 100%. HSP-70 was positive in 14 of 30 LG-HCCs and 0 of 18 adenomas. The sensitivity was 46% and the specificity was 100%. GS was positive in 24 of 30 LG-HCCs and 9 of 18 adenomas. The sensitivity was 80% and the specificity was 50%., Conclusions: GPC-3 and HSP-70 are helpful in separating carcinomas from adenomas. GS is not useful in this clinical context.