Histologic Demonstration Of Helicobacter Pylori In Gastric Biopsies: Which Is The Best Staining Method?

摘要

Aims: We have investigated the specificity and sensitivity of different histochemical and immunohistochemical methods for the detection of Helicobacter pylori (HP) on tissue sections of gastric biopsies. In addition, interobserver agreement of different staining methods was also evaluated in order to define the most reliable, the cheapest and most easily applicable method for the detection of HP.Methods: In this study 60 cases of HP positive and 10 HP negative cases were selected based on the results of urease test, C urease breath test and histopathologic examination of the tissue sections. Histopathologic examination was performed by Hematoxylin-Eosin (H&E), Toluidine Blue (TB), modified Giemsa (G) and HP immunohistochemistry. The sections were evaluated by two blinded pathologists. The interobserver agreement of the two pathologists was analyzed by Kappa ( κ) statistics.Results: The agreement between two observers was κ: 0.772 (96%) for HP immunostain; κ: 0.752 (92%) for modified Giemsa stain; κ: 0.487 (76%) for TB; and κ: 0.477 (80%) for H&E stain. The sensitivity and specificities for the stains were as follows: HP immunostain; 100% /100%, Giemsa stain; 97 %/90%, TB stain; 73%/90%, H&E; 97%/80%.Conclusion: HP can be detected on tissue sections regardless of the stain performed. However, the best results are obtained by the immunohistochemical stains and the modified Giemsa stain. The costs, applicability and the reliability of the Giemsa stain make it a perfect candidate as an adjunct to diagnosis presence of HP on gastric biopsies. Introduction The existence of bacteria colonizing the gastric mucosa has been recognized for a long time. In the last years there have been numerous publications revealing the role of HP in the pathogenesis of gastric carcinomas, gastric M.A.L.T. lymphomas and peptic ulcer disease (1,2,3,4,5,6,7,8,9,10,11). HP infection was classified by the World Health Organization (WHO) and the International Agency for Research on Cancer (IARC) in 1994 as a group-1 carcinogen in humans. This conclusion was based mainly on epidemiological findings (10,11). HP is one of the most prevalent infections in the world. The incidence of HP in healthy people in their 3 rd decades is 10% while the incidence of HP rises to over 60% among people in their 6 th decades (1,2,3,4,5,6,7). Gastric cancer is a multifactorial disease, where environmental, genetic factors and HP interact in a complex way (3,4,7,8,10,11). Only a minority of HP-infected individuals develops gastric cancer. Furthermore, it has been shown that this bacterium is not directly mutagenic in an Ames test. Then, it has been proposed that HP may act as a tumor promoter by changing proliferation and apoptosis of the gastric epithelium. Spontaneous eradication of HP has not been reported.HP is usually localized in the apical portion of the foveolar glands and does not penetrate the gland cytoplasm. HP colonization usually triggers an inflammatory reaction in the lamina propria. This process eventually leads to loss of mucin and atrophy of the glands (6,8). Urease activity of the bacteria leads to production of ammonia that is cytotoxic to the mucosa. HP is also known to produce extracellular toxins. In summary, HP metabolic products possibly cause transformation of the mucosa while the immune response is thought to play a role in the carcinogenesis associated with HP (8,13,14,15). Considering the role played by HP in the various processes mentioned above, it is critical to establish diagnostic tests which are both sensitive and specific enough to enable detection of HP. Currently there are several serologic, biochemical, molecular and histochemical methods available such as rapid urease test, C-urease breath test and histochemical and immunohistochemical stains for tissue sections (16,17,18,19). Histopathological detection of HP is accepted as a reliable and reproducible method. In order to detect HP on tissue sections, several cytochemical stains have been