ALK probe rearrangement in a t(2;11;(2)under-bar)(p23;p15;(q31)double-under-bar) translocation found in a prenatal myofibroblastic fibrous lesion: Toward a molecular definition of an inflammatory myofibroblastic tumor family?

A prenatal tumor located in the lumbar paravertebral area was discovered du ring a routine ultrasound examination at 32 weeks of pregnancy and surgical ly removed at 4 months of life. The histopathological diagnosis was first s uggested to be an infantile desmoid fibromatosis. The tumor karyotype showe d a three-way translocation involving both chromosomes 2 and a chromosome I I, t(2;11;2)(p23;p 15;q31). Fluorescence in situ hybridization with a prob e flanking the ALK gene at 2p23 demonstrated a rearrangement, as previously described in inflammatory myofibroblastic tumors (IMTs). In light of the g enetic analysis, the histopathological diagnosis was revised to IMT, althou gh inflammatory cells were scarce. IMTs are pseudosarcomatous inflammatory lesions that primarily occur in the soft tissue and viscera of children and young adults. Our report describes for the first time the occurrence of IM T during prenatal life. The ALK rearrangement may represent the molecular d efinition of a subgroup of mesenchymal tumors, not always with complete mor phological features of IMT, similar to the model of EWS rearrangement in th e Ewing sarcoma family of tumors. (C) 2001 Wiley-Liss, Inc.