Soft Tissues: Desmoplastic small round cell tumor

1999-05-01   Christine Pérot 

Clinics and Pathology

Phenotype stem cell origin

thought to be of peritoneal blastomatous cell origin


rare; mostly in childhood and adolescent males (mean age: 22 yrs; sex ratio: 4.7 M/1F)


very aggressive tumor, located almost exclusively to the peritoneal surfaces of the abdomen with involvement of many abdominal organs; very rare localisations outside the abdominal cavity (thoracic, cranial or skeletal localisations)


characterized by nested pattern of small poorly differenciated tumor cell growth surrounded by dense desmoplastic stroma and immunohistochemistrical trilineage coexpression: epithelial (cytokeratin, EMA), mesenchymatous (desmin, vimentin) and neural (NSE)


surgery may be performed before intensive chemo and radiotherapy


very poor; 35% overall progression-free survival at 5 yrs; median survival of about 17 months, although tumors are responsive to aggressive therapy in some cases


Atlas Image
Figure 1: t(11;22)(p13;q12) G- banding - Courtesy Galina Aldrete and Charles D. Bangs


besides the specific t(11;22)(p13;q12), 2 variant translocations have been described
Atlas Image
Figure 2: EWSR1 breakapart FISH of formalin-fixed paraffin-embedded section showing EWSR1 rearrangement - Courtesy Gail Aldrete and Charles D. Bangs

Additional anomalies

frequent additionnal abnormalities, sometimes complex


the variant translocations are (t(2;21;22)(p23;q22;q13) and t(11;17)(p13;q11.2)

Genes Involved and Proteins

Gene name

EWSR1 (Ewing sarcoma breakpoint region 1)



Dna rna description

spans over 40 kb, 17 exons ; 2,4 kb mRNA

Protein description

656 amino acids; N-term gln-thr-pro-rich region; C-terminal proline rich region; wide expression; RNA binding protein

Gene name

WT1 (Wilms tumor suppressor gene)



Dna rna description

spans over 50 kb, 10 exons; alternative splicings (in particular, the second site adds or remove 3 amino-acids (KTS) between the second and third zinc fingers and generates 2 isoforms); mRNA 3,5 kb

Protein description

52-54 Kda; 4 Cys2-His2 zinc fingers, glutamine- proline-glycine-rich transcriptional regulation domain, interacting with p53; nuclear localisation; transcriptional repressor

Result of the chromosomal anomaly


5EWS- 3WT1


mRNA detectable by RT-PCR (99% of DSRCT)


the N-term trans activation domain of EWS (exon 7) is fused to the C-term zinc fingers domain of WT1(exon 8); molecular variants have been described (exons 9 or 10 of EWS); transcritional activator ; the 2 isoforms EWS-WT1 without KTS and EWS-WT1 with KTS having different properties

Expression localisation



early: in the embryonal mesenchyme of the coelomic cavities; due to inapopriate transcriptional activition of WT1- responsive genes; the EWS-WT1 without KTS isoform would be dominantly acting as an oncogene


Pubmed IDLast YearTitleAuthors
96460311998Molecular variants of the EWS-WT1 gene fusion in desmoplastic small round cell tumor.Antonescu CR et al
86048061996Detection of the EWS/WT1 gene fusion by reverse transcriptase-polymerase chain reaction in the diagnosis of intra-abdominal desmoplastic small round cell tumor.Argatoff LH et al
88270701996Fusion of the EWS1 and WT1 genes as a result of the t(11;22)(p13;q12) translocation in desmoplastic small round cell tumors.Benjamin LE et al
76874541993Translocation (11;22)(p13;q12): primary change in intra-abdominal desmoplastic small round cell tumor.Biegel JA et al
97385721998Clinical, pathologic, and molecular spectrum of tumors associated with t(11;22)(p13;q12): desmoplastic small round-cell tumor and its variants.Gerald WL et al
17095571991Intra-abdominal desmoplastic small round-cell tumor. Report of 19 cases of a distinctive type of high-grade polyphenotypic malignancy affecting young individuals.Gerald WL et al
78626271995Characterization of the genomic breakpoint and chimeric transcripts in the EWS-WT1 gene fusion of desmoplastic small round cell tumor.Gerald WL et al
95917811998The desmoplastic small round cell tumor t(11;22) translocation produces EWS/WT1 isoforms with differing oncogenic properties.Kim J et al
86893451996Desmoplastic small cell tumor: a report of three cases and a review of the literature.Kretschmar CS et al
81870631994Fusion of the EWS and WT1 genes in the desmoplastic small round cell tumor.Ladanyi M et al
83748941993A recurring translocation, t(11;22)(p13;q11.2), characterizes intra-abdominal desmoplastic small round-cell tumors.Rodriguez E et al
13145221992A novel reciprocal chromosome translocation t(11;22)(p13;q12) in an intraabdominal desmoplastic small round-cell tumor.Sawyer JR et al
14865721992Cytogenetic abnormalities in an intraabdominal desmoplastic small cell tumor.Shen WP et al
109716962000Cytogenetic evidence of clonality in cutaneous benign fibrous histiocytomas: a report of the CHAMP study group.Vanni R et al
74952831995Detection of chimeric transcripts in desmoplastic small round cell tumor and related developmental tumors by reverse transcriptase polymerase chain reaction. A specific diagnostic Alava E et al


Christine Pérot

Soft Tissues: Desmoplastic small round cell tumor

Atlas Genet Cytogenet Oncol Haematol. 1999-05-01

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