Correlation Between Histological Evaluation and PCR-based Clonality Analysis of Gastric MALT Lymphomas Treated by Eradication of Sumie Takase

Mucosa-associated lymphoid tissue lymphoma (MALT lymphoma)arises from Helicobacter pylori (H. pylori)-associated chronic gastritis,and eradication of H. pylori is an effective treatment in most cases. Using Wotherspoon and Isaacson’s scoring system for the evaluation of gastric MALT lymphoma, in which grades up to 3 are considered reactive and grades 4 and 5 neoplastic,we assessed the histological findings of gastric biopsied specimens after eradication of H.pylori,and examined the relationship between the grade and the PCR-based monoclonality or the MIB-1 index. Expression of Ki-67 (MIB-1)antigen was examined immunohistochemically in 17 biopsied specimens from 3 patients,and 59 samples taken from these specimens were analyzed by PCR for immunoglobulin heavy chain gene rearrangement. Monoclonality was observed in 88%, 67%, and 17% of grade 5, 4 and 3 samples, respectively. No monoclonal band was detected in the samples of grades 1 and 2. The MIB-1 indices (mean±SD)in the interfollicular areas of grade 1 to 5 were 0.9±0.7,0.9±0.2,1.1±0.6,1.5±0.5,and 2.9± 1.6%, respectively. It is concluded that there is a good correlation between histological scoring and PCR-based monoclonality as well as MIB-1 indices.