PRIMARY GASTRIC LYMPHOMAS (MALTOMAS) - A NUCLEAR IMAGE-ANALYSIS COMPARISON WITH LYMPH-NODE MONOCYTOID B-CELLS AND MARGINAL ZONES OF SPLEEN AND PEYERS-PATCHES

Centrocyte-like cells of marginal zones of follicles of gastrointestin al lymphoid tissue, which have their analogous in marginal zone of spl enic white pulp and in lymph node monocytoid B-lymphocytes, are though t to be the normal counterpart of lymphomas of MALT (MALTomas). Howeve r, the cell population of MALTomas is often polymorphic and also conta ins cells morphologically different from centrocytes. Since convention al morphologic analysis may be not accurate enough and the phenotype m ay change in different stages of B-cell lineage, the marginal zone of Peyer's patches (PMZ) and splenic white pulp (SMZ), the lymph node mon ocytoid B-lymphocytes (ML), 3 nodal monocytoid B-cell lymphomas (L) an d 16 gastric MALTomas (M) were studied by means of automated nuclear i mage analysis for area, irregularity, and chromatin texture assessment . Immunophenotyping on paraffin sections and polymerase chain reaction (PCR) for detecting monoclonality and t(14-18) chromosome breakpoints at DNA levels, on paraffin section extractions, were also done. In 14 MALTomas, clonal Ig heavy chain rearrangement was detected and in non e of these were found t(14-18) chromosome breakpoints. The nuclei of t he control group (PMZ, SMZ and ML) showed the same morphologic charact eristics, ie. size, irregularity, chromatin texture. MALTomas and noda l lymphomas were distributed into 3 clusters: (I)with larger nuclei, l ight chromatin (euchromatin-richer) (5 MALTomas, 2 nodal lymphomas tog ether with the control group); (2) nuclei with the same area size, but darker (eterochromatin-richer) (6 MALTomas and 1 nodal lymphoma); (3) with smaller and darker nuclei (5 MALTomas). Chromatin textural diffe rences were maintained in the same nuclear size class in the 3 cluster s. Only a few MALTomas had nuclear features not significantly differen t from controls, inter-case and intra-case variability being evident.