title: Atypical lipomatous tumor with structural rearrangements involving chromosomes 3 and 8.
abstract: Atypical lipomatous tumor (ALT) is an intermediate (locally aggressive) mesenchymal neoplasm with the potential to dedifferentiate to higher grades over time. It is cytogenetically characterized by the presence of one or more supernumerary ring and giant marker chromosomes. These abnormal chromosomes invariably contain amplified sequences derived from the 12q14-15 region. We describe a unique cytogenetic finding of ALT arising in the right lower back of a 42-year-old man. Magnetic resonance imaging demonstrated a predominantly fatty mass with irregularly thickened, linear, swirled, and nodular septa. Contrast-enhanced fat-suppressed T1-weighted images showed significant enhancement of the non-adipose areas. A sub-extensive resection was performed. Histologically, the tumor consisted predominantly of mature fat cells with atypical stromal cells and multivacuolated lipoblasts. Immunohistochemically, the tumor cells were positive for p16 (diffuse and strong signal) and cyclin-dependent kinase-4 (focal and weak signal) but negative for murine double-minute 2. Cytogenetic analysis displayed a t(3;8)(q28;q13) translocation as the sole anomaly or concomitant with a few other numerical and structural alterations. There has been no evidence of local recurrence two months after surgery. To the best of our knowledge, this is the first case of ALT with structural aberrations involving chromosomes 3 and 8, associated with an absence of 12q rearrangements.
authors.affiliation: Department of Orthopaedic Surgery, Faculty of Medicine, Fukuoka University, Fukuoka, Japan jnishio@cis.fukuoka-u.ac.jp.
authors.forename: Jun
authors.initials: J
authors.lastname: Nishio
authors.affiliation: Department of Pathology, Faculty of Medicine, Fukuoka University, Fukuoka, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Iwasaki
authors.affiliation: Department of Pathology, Faculty of Medicine, Fukuoka University, Fukuoka, Japan.
authors.forename: Kazuki
authors.initials: K
authors.lastname: Nabeshima
authors.affiliation: Department of Orthopaedic Surgery, Faculty of Medicine, Fukuoka University, Fukuoka, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Kamachi
authors.affiliation: Department of Orthopaedic Surgery, Faculty of Medicine, Fukuoka University, Fukuoka, Japan.
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Naito
mesh_terms: D000328:Adult; D002881:Chromosomes, Human, Pair 12 / Q000235:genetics*; D002898:Chromosomes, Human, Pair 8 / Q000235:genetics*; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008067:Lipoma / Q000235:genetics / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D011379:Prognosis; D014178:Translocation, Genetic / Q000235:genetics*
keywords: Atypical lipomatous tumor; cytogenetics; lipoma; p16; well-differentiated liposarcoma