Recurrent involvement of 2p23 in inflammatory myofibroblastic tumors.

Inflammatory myofibroblastic tumor (IMT) is a relatively rare soft tissue tumor. The reactive versus neoplastic pathogenesis of this tumor is unresolved. We found clonal chromosome aberrations involving 2p23 upon metaphase analysis of two IMTs. Fluorescence in situ hybridization with a probe flanking the ALK gene at 2p23 demonstrated rearrangement of the probe in both of these cases and in a third case, and immunohistochemistry revealed ALK expression in all three cases. 2p22-24 involvement has been reported previously in four additional cases of IMT. We suggest that chromosomal rearrangements involving 2p23 near or within ALK are recurrent alterations in IMT and that ALK may have a novel role outside its previously recognized realm of lymphoid neoplasms.