Soft tissue tumors: Lipoblastoma

Classification

Two forms of the tumor lesion have been described: encapsulated circumscribed type (lipoblastoma), and a noncapsulated diffuse infiltrative type (lipoblastomatosis).

Clinics and Pathology

Disease	Benign uncommon soft-tissue tumor of embryonal fat.
Embryonic origin	Develops from embryonic remnants of white fat tissue.
Epidemiology	Primarily occurs in young children (<3 years) prevalently male.
Clinics	Presents in superficial tissues of arms and legs (deeper in lipoblastomatosis), though mediastinum, retroperitoneum, trunk, head and neck may be affected.
Pathology	Lobulated tissue composed of immature fat cells separated by fibro-vascular septa and areas with a myxoid matrix. The lobules contain lipoblasts in different stages of differentiation, ranging from primitive, spindle-shaped cells to lipoblasts simulating mature fat cells. Differential diagnosis, particularly in older children or in diffuse lipoblastoma, include myxoid liposarcoma and atypical lipoma and may be based on distinct cytogenetic abnormalities.
Treatment	Surgical excision.
Prognosis	These tumors have an excellent prognosis but local recurrence is possible expecially in diffuse lesions.

Cytogenetics

Cytogenetics Morphological	Pseudodiploid karyotype with clonal chromosomal rearrangements involving the 8q11-13 region. Gain of chromosome 8 is reported.
Cytogenetics Molecular	Detectable by metaphase and/or interphase FISH using specific PLAG1 probes.
	Dual-color FISH analysis in a case of lipoblastoma with complex structural rearrangement: RP11-140I16 (PLAG1) (red) was cohybrized with RP11-299N14 (HAS2) (green). Arrow indicates PLAG1-HAS2 fusion signal on the der(8), arrowhead indicates the normal chromosome 8. The BAC clones were provided by Prof. M.Rocchi.
Probes	RP11-140I16, BAC227k20, YAC164H5, RP11-299N14, YAC947h7.

Genes involved and Proteins

Gene Name	PLAG1
Location	8q12.1
Dna / Rna	7313 bp mRNA
Protein	PLAG1, (together with PLAGL1 and PLAGL2), belongs to a subfamily of C2H2 zinc finger transcription factors that activate transcription.

Gene Name	HAS2
Location	8q24.12

Gene Name	COL1A2
Location	7q22.1

Result of the chromosomal anomaly

Hybrid Gene
Note	HAS2-PLAG1, COL1A2-PLAG1 Chromosomal rearrangements in tumor tissue determine PLAG1 transcriptional up-regulation.
Description	The 8q12 rearrangement results in a promoter-swapping event, whereby the PLAG1 promoter element is replaced by promoting regions from other genes, notably hyaluronic acid synthase 2 (HAS2) or collagen 1 a 2 (COL1A2). 5' HAS2 - 3' PLAG1 fused after an 8q intrachromosomal rearrangement that determined the juxtaposition of band 8q12.1 to 8q24.1. The breakpoint of HAS2 gene is in intron 1, whereas its coding sequence starts at the first codon of exon 2. 5' COL1A2 - 3' PLAG1 has been described in one case of t(7;8)(p22;q13)
Transcript	Alternative splicing variants which included or lacked PLAG1 exon 2.
Fusion Protein
Description	HAS2-PLAG1 and COL1A2-PLAG1 both encode a full-lenght PLAG1 protein.

Bibliography

Benign lipoblastomatosis: an analysis of 35 cases

Chung EB, Enzinger FM.

Cancer 1973; 32: 482-492.

PMID 4353020

Chromosome abnormalities in two benign adipose tumors.

Sandberg AA, Gibas Z, Saren E, Li FP, Limon J, Tebbi CK.

Cancer Genet Cytogenet 1986; 22: 55-61.

PMID 3456828

Lipoblastoma: a case with t(7;8)(q31;q13)

Panarello C, Rosanda C, Morerio C, Russo I, Dallorso S, Gambini C, Ricco AS, Storlazzi T, Archidiacono N, Rocchi M.

Cancer Genet Cytogenet 1998; 102: 12-14.

PMID 9530333

Evidence of involvement of the PLAG1 gene in lipoblastomas.

Astrom AK, D'Amore ESG, Sainati L, Panarello C, Morerio C, Mark J, Stenman G.

Int J Oncol 2000; 16: 1107-1110.

PMID 10811981

Evidence by spectral karyotyping that 8q11.2 is nonrandomly involved in lipoblastoma.

Chen Z, Coffin CM, Scott S, Meloni-Ehrig A, Shepard R, Issa B, Forsyth DR, Sandberg AA, Brothman AR, Lowichik A.

J Mol Diagn 2000; 2: 73-77.

PMID 11272891

PLAG1 Fusion oncogenes in lipoblastoma.

Hibbard MK, Kozakewich HP, Dal Cin P, Sciot R, Tan X, Xiao S, Fletcher J.

Cancer Res 2000; 60: 4869-4872.

PMID 10987300

PLAG1 alterations in lipoblast

Gisselsson D, Hibbard MK, Dal Cin P, Sciot R, Hsi B-L, Kozakewich HP, Fletcher JA.

Am J Pathol 2001; 159: 955-962.

PMID 11549588

Lipoblastoma and lipoblastomatosis: a report of two cases and review of the literature.

Harrer J, Hammon G, Wagner T, Bolkenius M.

Eur J Pediatr Surg 2001; 11: 342-349. (REVIEW)

PMID 11719876

Atypical lipomatous tumor in a 14-year-old patient: distinction from lipoblastoma using FISH analysis.

Kuhnen C, Mentzel T, Fisseler-Eckhoff A, Debiec-Rychter M, Sciot R.

Virchows Arch 2002; 441: 299-302

PMID 12242528

Updates on the cytogenetics and molecular genetics of bone and soft tissue tumors: lipoma.

Sandberg AA.

Cancer Genet Cytogenet 2004; 150: 93-115. (REVIEW)

PMID 15066317

PLAG1-HAS2 fusion in lipoblastoma with masked 8q intrachromosomal rearrangement

Morerio C, Rapella A, Rosanda C, Tassano E, Gambini C, Romagnoli G, Panarello C.

Cancer Genet Cytogenet 2005; 156: 183-184.

PMID 15642402

REVIEW articles	automatic search in PubMed
Last year publications	automatic search in PubMed

Contributor(s)

Written	01-2005	Cristina Morerio, Claudio Panarello

Citation

This paper should be referenced as such :

Morerio C, Panarello C . Soft tissue tumors: Lipoblastoma. Atlas Genet Cytogenet Oncol Haematol. January 2005 . URL : http://AtlasGeneticsOncology.org/Tumors/LipoblastomaID5155.html

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indexed on : Thu Apr 17 14:14:35 2008

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