Primary gastric B cell lymphoma: audit of 82 cases treated with surgery and classified according to the concept of mucosa-associated lymphoid tissue lymphoma.

There has been a trend toward stomach conservation during treatment for primary gastric lymphoma, but surgery ensures accurate pathologic diagnosis through the examination of resected specimens. A histopathologic classification for primary gastric lymphoma had been established with the knowledge that the low grade and high grade components occasionally coexist in a single lesion. Efficacy of this classification as an indicator of biologic behavior and prognosis was evaluated. The classification was performed by reexamining surgically resected specimens from 82 patients with stage IE and IIE gastric lymphoma. Clinical characteristics of the low grade and high grade lymphomas were then evaluated and the survival data analyzed. Despite the larger tumor diameter, the depth of invasion for the low grade type was mostly submucosal, and none had serosal invasion. In contrast, 50% of the high grade type had serosal involvement and were also found to have a higher incidence of node metastasis. Prognosis of the low grade type, a 10-year survival rate exceeding 90%, was significantly better than that of the high grade type. Multivariate analysis revealed that curability of the operation followed by the histopathologic grade were significant independent prognostic factors. Some characteristics of the low grade lymphoma were not consistent with what has been reported in the studies involving stomach-conserving strategies. Investigators are advised to note that the histopathologic grade determined with biopsy specimens alone could be misleading.