title: IgH PCR of zinc formalin-fixed, paraffin-embedded non-lymphomatous gastric samples produces artifactual "clonal" bands not observed in paired tissues unexposed to zinc formalin.
abstract: Helicobacter pylori (HP) causes dense gastritis that can be difficult to distinguish morphologically from MALT-type lymphoma (ML). Immunoglobulin heavy chain (IgH) gene analysis by polymerase chain reaction (PCR) is often used to resolve diagnosis. However, monoclonal bands have been reported in nonmalignant cases of gastritis. Retrospectively, 16 gastric ML with both formalin-fixed, paraffin-embedded (FF-PE) and ethanol-fixed samples (EF), and 9 cases of FF-PE HP-gastritis were analyzed by IgH PCR to document the presence of non-reproducible bands in HP-gastritis, but not ML samples. In duplicate analyses, 12 of 16 ML yielded identical monoclonal bands in FF-PE and EF samples whereas 3 of 9 FF-PE gastritis cases yielded different-sized (ie, non-reproducible) "clonal" bands. Sequencing of two PCR products from a gastritis case confirmed IgH gene sequences. To investigate whether FF-PE had a direct effect on producing these non-reproducible bands, 7 gastrectomy samples were prospectively divided into EF and FF-PE halves for IgH PCR. All 7 samples demonstrated polyclonal smears in EF portions while 4 of 7 FF-PE portions yielded either multiple distinct bands or non-reproducible bands. In conclusion, IgH PCR of FF-PE tissue can create artifactual "clonal" bands, which are the appropriate product size, contain IgH sequences, and, if not performed in duplicate, may confuse interpretation of B-cell clonality.
authors.affiliation: Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, Florida 32610-0275, USA. ahrens@pathology.ufl.edu
authors.forename: Kim
authors.initials: K
authors.lastname: Ahrens
authors.forename: Raul
authors.initials: R
authors.lastname: Braylan
authors.forename: Nidal
authors.initials: N
authors.lastname: Almasri
authors.forename: Robin
authors.initials: R
authors.lastname: Foss
authors.forename: Lisa
authors.initials: L
authors.lastname: Rimsza
mesh_terms: D001483:Base Sequence; D017931:DNA Primers; D005557:Formaldehyde; D005756:Gastritis / Q000235:genetics / Q000382:microbiology / Q000473:pathology; D016481:Helicobacter Infections / Q000235:genetics / Q000382:microbiology / Q000473:pathology; D016480:Helicobacter pylori / Q000302:isolation & purification; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000235:genetics*; D018442:Lymphoma, B-Cell, Marginal Zone / Q000235:genetics* / Q000473:pathology; D008969:Molecular Sequence Data; D016612:Paraffin Embedding; D016133:Polymerase Chain Reaction / Q000379:methods*; D012189:Retrospective Studies; D013274:Stomach Neoplasms / Q000235:genetics* / Q000473:pathology; D016707:Tissue Fixation; D015032:Zinc
chemical_list: D017931:DNA Primers; D007143:Immunoglobulin Heavy Chains; D005557:Formaldehyde; D015032:Zinc