F IGH MALT1; FP IGH MALT1
t(14;18)(q32;q21), Immunoglobulin heavy chain / Mucosa associated lymphoid tissue lymphoma translocation gene 1
Fluorescence in situ Hybridization (FISH)
F IGH MALT1
2.0 mL (min. 1.0 mL) peripheral blood in sodium heparin preferred, EDTA accepted
1.0 mL (min. 0.5 mL) bone marrow in sodium heparin preferred, EDTA accepted
5 mm^3 fresh tissue or 3.0 mL (min. 2.0 mL) FNA in MPLN RPMI medi
FP IGH MALT1
10% neutral buffered formalin fixed paraffin embedded tissue
Whole blood and bone marrow, ship ambient
Fresh tissue, FNA or paraffin embedded tissue, ship in a Styrofoam container with a cool/refrigerated pack (Do not allow cool pack to directly contact sample)
Clotted specimen; Specimen exposed to extreme temperature; Anticoagulant toxic to cells; Insufficient number of cells; Improper fixative
In a normal cell, a two orange, two green signal pattern is observed reflecting two intact copies of MALT1 and IGH, respectively. In an abnormal cell containing only the t(14;18)(q32;q21) translocation, a one orange, one green, and two fusion signal pattern is observed.
Translocation (11;18)(q21;q21) has been associated with extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma). Translocation (11;18) leads to the fusion of the apoptosis inhibitor-2 (API2) gene and the MALT lymphoma-associated translocation (MALT1) gene. However, it has been found that 18% of MALT lymphomas have t(14;18)(q32;q21) or a translocation involving the IGH and MALT1 gene. MALT lymphomas with t(11;18)(q21;q21) usually do not have additional genetic aberrations, which is in contrast to t(14;18)(q32;q21) cases. Aneuploidy is seen in the majority of t(14;18)(q32;q21) MALT lymphomas.
FISH can detect this rearrangement in either interphase or metaphase cells.