What changed: High-grade B-cell lymphoma with MYC and BCL2 rearrangements (double-hit lymphoma)

When this page itself was last checked or edited.

Every aggressive B-cell lymphoma biopsy is tested by fluorescence in situ hybridisation for MYC, and if MYC is rearranged, for BCL2 and BCL6. A lymphoma cannot be identified as double-hit by appearance, by immunohistochemistry for MYC and BCL2 protein, or by the cell-of-origin assay; dual protein expression is a separate and much commoner finding with its own, lesser, prognostic weight. Follicular lymphoma is excluded from the entity by both classifications even when it carries both rearrangements.

Both removed cases with MYC and BCL6 rearrangements from the double-hit entity. WHO-HAEM5 reassigns them by appearance; the International Consensus Classification made them a provisional entity of their own.

An analysis of 157 germinal-centre diffuse large B-cell lymphomas defined a 104-gene double-hit signature present in 27 per cent of them, only half of which carried the rearrangements; those with the signature had a five-year time to progression of 57 per cent against 81 per cent.

The revised fourth edition of the WHO classification created high-grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements as a category of its own, which made testing for the rearrangements routine.