title: HMGA2-NFIB fusion in a pediatric intramuscular lipoma: a novel case of NFIB alteration in a large deep-seated adipocytic tumor.
abstract: Lipomas are frequently characterized by aberrations of the 12q13 approximately q15 chromosomal region and often by rearrangements of the HMGA2 gene. These rearrangements include the formation of chimeric genes that fuse the 5' region of HMGA2 with a variety of partners, such as LPP (3q28) or NFIB (9p22). We describe here the fourth reported case of lipoma showing a HMGA2-NFIB fusion, and the first one in a child. We found a translocation t(9;12)(p22;q14) in a deep-seated intramuscular lipoma occurring in the buttock of a 5-year-old boy. By fluorescence in situ hybridization and reverse-transcription polymerase chain reaction, we have shown that the translocation t(9;12) resulted in an in-frame fusion of the first four exons of HMGA2 with the last exon of NFIB. Intramuscular lipomas are very rare in childhood. Our results confirm that lipomas containing NFIB rearrangements may be related to peculiar clinicohistologic features, including large size, deep situation, infiltration of surrounding muscles, or precocious occurrence. Both the truncation of HMGA2 and the nature of its fusion partner gene might be relevant in the adipose tissue tumorigenesis.
authors.affiliation: Faculty of Medicine, Laboratory of Solid Tumor Genetics, Nice University Hospital, 06107 Nice cedex 2, France.
authors.forename: Anne
authors.initials: A
authors.lastname: Pierron
authors.forename: Carla
authors.initials: C
authors.lastname: Fernandez
authors.forename: Esma
authors.initials: E
authors.lastname: Saada
authors.forename: Frédérique
authors.initials: F
authors.lastname: Keslair
authors.forename: Géraldine
authors.initials: G
authors.lastname: Hery
authors.forename: Hélène
authors.initials: H
authors.lastname: Zattara
authors.forename: Florence
authors.initials: F
authors.lastname: Pedeutour
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism*; D002648:Child; D020732:Cytogenetic Analysis; D025743:HMGA2 Protein / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008067:Lipoma / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D008297:Male; D051839:NFI Transcription Factors / Q000235:genetics* / Q000378:metabolism; D015514:Oncogene Proteins, Fusion / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017421:Sequence Analysis
chemical_list: D025743:HMGA2 Protein; D051839:NFI Transcription Factors; C110754:NFIB protein, human; D015514:Oncogene Proteins, Fusion