Do you routinely order double-hit assessment in cutaneous DLBCL?

There are certainly reported cases of primary cutaneous DLBCL that harbor double-hit mutations. Guidelines do not distinguish the workup of cutaneous DLBCL from other sites, and if a skin DLBCL were to be of germinal center immunophenotype with IHC expression of myc and bcl2 and/or bcl6, FISH would certainly be standard. Restricting FISH to GCB that is IHC+ will miss a small percentage of double-hit cases, of course, so maintaining an index of suspicion in unusual settings (very high proliferati...