Classification of Gastrointestinal B-cell Lymphoma and Expression of Cyclin D1, bcl-2, bcl-6, p53 Protein and PCNA

ABSTRACT

Until recently, the gastrointestinal lymphomas were classified according to the criteria developed for the node-based lymphomas. In recent years, the REAL classification provided a new category of MALT lymphoma and Mantle cell lymphoma in B-cell lymphomas. Low-grade MALT lymphomas have been well characterized clinically, histologically, and immunophenotypically. We retrospectively recategorized 41 cases of the primary gastrointestinal B-cell lymphoma and investigated the expression of cyclin D1, bcl-2, bcl-6, p53 protein, and PCNA by immunohistochemical method. The cases were categorized in 5 groups, low grade MALToma, low/high grade MALToma, high grade MALToma, diffuse large cell lymphoma, and mantle cell lymphoma according to the morphological findings. The expression of cyclin D1 protein was restricted to the cases of mantle cell lymphoma. The bcl-2 protein expression was higher in the low grade MALT lymphoma than in the high grade lymphoma (P=0.006). The bcl-2 protein expression was higher in the low grade area than in the high grade area in the low/high grade MALT lymphoma (P=0.005). The bcl-6 and p53 protein expression was higher in the high grade MALT lymphoma than in the low grade lymphoma (P=0.022, P<0.018). However, the bcl-6 protein expression of the tumor cells was higher in high grade area than in low grade area in the low/high grade MALT lymphoma (P=0.004). The degree of the PCNA expression was positively correlated with the grade of the malignant lymphoma (P=0.003). The above results suggest that the cellular proliferation assessed by PCNA index correlates with the histologic grade. And the bcl-2, bcl-6, p53 protein may be effective in the transition from the low grade MALT lymphoma to the high grade lymphoma. Therefore, we can differentiate the low grade lymphoma from the high grade lymphoma by the immunohistochemical staining for cyclin D1, bcl-2, bcl-6, p53 protein and can predict the prognosis of the patients in accordance with the grade of the tumor.