Genetic alteration in inflammatory myofibroblastic tumor
Most IMTs with ALK fusion at other organs involve ALK exon 20, whereas ALK fusion involving exon 18 or 19 has been reported only in genitourinary IMTs with a gene fusion partner FN1. With review of the clinicopathological characteristics of such cases, we suggest that the presence of FN1-ALK fusions with ALK exon 18 or 19 rearrangements may be specific to a subset of IMTs arising in the urinary bladder.