[Clinical and morphological aspects of MALT-gastric lymphoma]

Abstract

Mucosa-associated lymphoid tissue (MALT) conception has been extensively developing for last 20 years.

The aim: The aim of this work was to elaborate clinico-morphological and immunohistochemical criteria of gastric MALT-lymphomas and to differentiate them from another with similar histology.

Materials and methods: Between 1983 and 2007, 704 patients with diagnosis of extranodal lymphoma were observed in Russian Cancer Research Center. The work included biopsy and postoperation samples from 115 patients with primary gastric lymphoma, who were observed in Russian Cancer Research Center since 1995. On presented material with primary lymphomas were elaborated morphological criteria of MALT-lymphoma diagnosis for gastrobiopsy, based on histological, immunohistochemical and genetic examination. Also were devised differential diagnostic criteria of MALT-lymphoma.

Results: Follow morphological signs were estimated: cell composition, atypia of neoplastic elements, presence of plasmocellular differentiation of lymphoid cells, expression of plasmocytary infiltration, lymphoepithelial lesion and reactive lymphoid follicles with or without colonization, presence of blasts. So, in 35.2% cases part of neoplastic elements had the aspect of monocytoid B-lymphocytes. In the most of observations were revealed plasmatic cells. More often they were under integumentary epithelium as massive layer (46.47%), more rare they were scattered in superficial sections of lamina propria among cells of leukocyte row (39.43%). Lymphoepithelial lesions (LELs) are aggregates from three and more marginal zone cells, destroyed epithelium of glands, were revealed in half of cases. In 17.14% cases were ("blast") LELs, generated by large blasts. For reactive process T-lymphocytes predominate over B-lymhpocytes in the lymphocellular infiltrate, or T-lymphocytes and B-lymhpocytes are in equal ratio. The next important sign is coexpression T-cell marker CD43 on neoplastic B-cells. Cases of MALT-lymphoma with t(11; 18) are resistant to the antihelicobacter therapy.

Conclusion: The most informative morphological, immunohistochemical features were ascertained as in diagnosis, as in differentiation with another neoplasms with similar morphology and reactive lymphoid infiltrates.