Clinicopathological comparison of the World Health Organization/Wotherspoon score to the Groupe d'Etude des Lymphomes de l'Adult grade for the post-treatment evaluation of gastric mucosa-associated lymphoid tissue lymphoma.

BACKGROUND AND AIM: The World Health Organization (WHO) has adopted criteria for the histological differential diagnosis of gastric extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (GML) based on the criteria proposed by Wotherspoon in 1993 (WHO/Wotherspoon score). These histological criteria are commonly used by pathologists for initial diagnoses, but have not been adopted uniformly for the post-treatment evaluation of GML. In 2003, the Groupe d'Etude des Lymphomes de l'Adult (GELA) proposed a new histological grading system (GELA grade) in preference to use of the WHO/Wotherspoon score for post-treatment evaluation. In the present study, we compared the WHO/Wotherspoon and GELA systems to examine which histological criterion is better for post-treatment evaluation.

METHODS: Fourteen cases of GML under long-term follow up were initially diagnosed according to the WHO criteria with detailed immunohistology, and were periodically evaluated with both histological criteria after anti-Helicobacter pylori treatment. They were also evaluated based on histological stromal changes accompanying the disappearance of lymphoma tissue.

RESULTS: The study showed strong similarities between the WHO/Wotherspoon and GELA systems and no clear advantage of either system for post-treatment evaluation. The GELA grade could not be used for the evaluation of changes in the degree of lymphoma infiltration from pre- to post-treatment because the four-item scale is not comparable with the formal six-point WHO/Wotherspoon scale. Stromal changes in the lamina propria, including an empty appearance and fibrosis, were correlated with lymphoma reduction after treatment and appear to be good indicators for post-treatment evaluation.

CONCLUSION: We propose the utilization of the WHO/Wotherspoon score accompanied by the assessment of stromal changes for the post-treatment evaluation of GML.