Splenic B-Cell Lymphoma/Leukemia With TCL1 Gene Rearrangement.

BACKGROUND

Splenic B-cell lymphoma/leukemia includes a group of indolent small B-cell lymphomas/leukemias that share overlapping morphological and immunophenotypic features, making accurate diagnosis challenging. Specific gene rearrangements have not been commonly associated with splenic B-cell lymphomas/leukemias, and the TCL1 gene rearrangement-characteristic of T-cell prolymphocytic leukemia-has not been previously reported in B-cell lymphomas/leukemias. Here, we report two unique cases of splenic B-cell lymphoma/leukemia harboring an IGH::TCL1 rearrangement.

CASE PRESENTATION: Patient #1 was a 74-year-old man with a 25-year history of low-grade B-cell leukemia involving the peripheral blood, spleen, and bone marrow. Patent #2 was a 54-year-old woman who recently presented with lymphocytosis and low-level bone marrow involvement. Both patients were asymptomatic and incidentally found to have lymphocytosis. The neoplastic cells in both cases displayed polar villous cytoplasmic projections, were of B-cell lineage, and were negative for CD5 and CD10. Notably, an IGH::TCL1 fusion was identified in both cases.

CONCLUSIONS

The identification of IGH::TCL1 fusion in these two cases of splenic B-cell lymphoma/leukemia suggests that TCL1 gene rearrangements can occur in B-cell lymphoma/leukemia and should not be considered exclusive to T-cell prolymphocytic leukemia. Accurate diagnosis of splenic B-cell lymphoma/leukemia with TCL1 rearrangement requires evaluation of morphologic and immunophenotypic features and genetic assessment of TCL1.