Primary Gastric Malignant Lymphoma: Subtype Features And Analysis Of The Bcl-6 Protein Expression

PGML represents a heterogeneous group of neoplasms which are quite different among the subtypes in pathogenesis , origin of tumor cell , sensitivity to treatment as well as prognosis .It is very significant for therapeutic option and prognostic evaluation to define the histological subtypes of PGML, and the uniform dense expression pattern of bcl-6 protein is associated with germinal center stages of B-cell differentiation , detection of the expression could be useful to evaluate the origin of tumor cell and identify the classification of subtypes. Combination of morphological and immunohistochemical methods ,36 cases PGML were subclassified according to the criteria of the WHO classification (2001) and all cases were explored the expression of bcl-6 protein in the subtypes. In our study ,21 cases are large cell lymphoma ,in which 8 cases are primary extronodal DLBCL , 13 cases are DLBCL concomitant with MALT lymphoma component , other 15 cases are small cell lymphoma; 14 and 1 cases exhibited positivity for bcl-6 and CD10, respectively; none of cases showed expression of CD5, CD10 and CD23 in small cell lymphomas , but two of them express nuclear cyclinD1 protein ; there are 3 cases primary DLBCLs ,4 cases DLBCLs concomitant MALT lymphoma component and 5 cases MALT lymphomas in which bcl-6 protein GC/FL expression patterns were observed. Finally, we identified that all cases were of B-cell NHL ,and were subclassified as DLBCL (21), extranodal marginal zone MALT lymphoma (13) and mantle cell lymphoma(2), so the aggressive lymphoma is more common than indolent lymphoma (63.9%v36.1); bcl-6 protein expression rate in primary gastric DLBCL is 33.3%(7/21) ,which is much lower than the data accquired in other organs; 5 cases MALT lymphomas and 4 cases DLBCL+MALT lymphomas revealed an aberrant GC/FL expression pattern of bcl-6 protein ,while the other germinal cell marker CD10 is negative in all these cases ,so the GC/FL expression pattern of bcl-6 protein can not be used to define the germinal center origin in our experiment.