Large B-cell lymphoma presenting in the spleen: identification of different clinicopathologic conditions.

Only a few series of splenic large B-cell lymphoma have been previously reported, including limited immunophenotypic studies and clinical data. Here we review the clinical data, morphology, and immunophenotype of series of 33 cases of large B-cell lymphoma presenting in the spleen. Three main groups of tumors are identified. Group A was characterized by macronodular tumors (20 cases), with predominantly stage I disease and a favorable clinical outcome. All cases were bcl6 positive. Group B was characterized by a micronodular pattern (nine cases), including a subset with T-cell-rich B-cell lymphoma features. Most of the patients in this group were diagnosed at advanced clinical stages and died of the disease. All cases were bcl6 positive. Group C was characterized by diffuse red pulp infiltration (four cases) and advanced clinical stages and showed an aggressive behavior. All but one case were bcl6 positive. The results of this series define a characteristic type of large B-cell lymphoma presenting in the spleen as a tumoral mass, associated with a relatively favorable clinical course. Additionally, they provide evidence that clinical presentation as a tumor confined to the spleen and the hilar lymph nodes is associated with lower aggressivity.

Analysis of the IgV(H) somatic mutations in splenic marginal zone lymphoma defines a group of unmutated cases with frequent 7q deletion and adverse clinical course.

This study aimed to correlate the frequency of somatic mutations in the IgV(H) gene and the use of specific segments in the V(H) repertoire with the clinical and characteristic features of a series of 35 cases of splenic marginal zone lymphoma (SMZL). The cases were studied by seminested polymerase chain reaction by using primers from the FR1 and J(H) region. The results showed unexpected molecular heterogeneity in this entity, with 49% unmutated cases (less than 2% somatic mutations). The 7q31 deletions and a shorter overall survival were more frequent in this group. Additionally a high percentage (18 of 40 sequences) of SMZL cases showed usage of the V(H)1-2 segment, thereby emphasizing the singularity of this neoplasia, suggesting that this tumor derives from a highly selected B-cell population and encouraging the search for specific antigens that are pathogenically relevant in the genesis or progression of this tumor.