Background: The differences in clinical presentation, morphology, phenotype and genetic changes between lymphomas originating in the gastrointestinal tract and the lymph nodes justified the proposal of a system of specific classification for lymphomas originating in lymphoid tissue associated to mucosa (MALT). Nevertheless, there is no conclusive evidence that the types of lymphoma defined as such have a different clinical evolution with respect to the lymph nodes lymphomas.
Methods: With the aim of analyzing this problem a clinical follow up of 33 patients with primary gastric lymphomas (high and low grade) was compared with the results of a group of 99 lymphomas of the lymph nodes was carried out with classification according to the criteria of Kiel classification and the proposal by Isaacson et al for MALT lymphomas. Survival obtained by the Kaplan-Meier method was compared by the Mantel-Haenzel test.
Results: The results obtained showed that all gastric lymphomas have a less aggressive evolution than those of lymph node origin (p < 0.01). This significant statistical difference was also observed when lymphomas of similar histology were compared. Similarly, the subgroups of large cell lymphoma (p < 0.05) and small cells (p < 0.01) differ with respect to lymphomas of similar histology and of lymph node origin. In contrast with the results expected, no significant difference was observed between the two main groups of lymphomas of high and low grade mucosal origin.
Conclusions: The analysis of the results supports the convenience of a system of specific classification for lymphomas of mucosal origin. Nevertheless, the specific existence of groups of high and low grade lymphomas is questioned since the probability of survival between both subgroups does not show statistically significant differences.