Clonal relationship between transformed and non-transformed components in mucosa-associated lymphoid tissue lymphoma

Abstract

To analyze the clonal relationship between transformed and non-transformed components in mucosa-associated lymphoid tissue (MALT) lymphoma. Six cases of MALT lymphoma with high-grade transformation were studied. Immunohistochemical study was carried out by EliVision using bcl-10 antibody. Reverse transcription-polymerase chain reaction was used to detect the presence of API2-MALT1 fusion gene transcripts. The target cells were selected by laser microdissection and studied by polymerase chain reaction and sequence analysis for rearrangement of immunoglobulin heavy chain gene. In the 6 cases of MALT lymphoma with high-grade transformation, nuclear and cytoplasmic expression of bcl-10 was demonstrated in 1 case, while API2-MALT1 fusion gene was present in 2 cases. Identical fragments of rearranged immunoglobulin heavy chain gene were detected in both transformed and non-transformed components in each of the 6 cases, except for the differences at 2 nucleotide positions in N or D regions in 2 cases. The tumor cells from both transformed and non-transformed components in MALT lymphoma derive from the same clone.