Sorted By Test Name - Mayo Medical Laboratories

FDXM
91956
FDEXA
91777
diagnosis, they cannot distinguish between DSRCT and other small-round-cell tumors. Expertise in soft
tissue and bone pathology are often needed. Studies have shown that some sarcomas have specific
recurrent chromosomal translocations. These translocations produce highly specific gene fusions that help
define and characterize subtypes of sarcomas and are useful in the diagnosis of these lesions.(1-4) DSRCT
is associated with a unique chromosomal translocation t(11:22)(p13;q12) that involves the EWSR1 and
the WT1 genes. EWSR1 is the breakpoint site of translocations associated with Ewing sarcoma and WT1
is a gene altered in some Wilms tumors. The translocation results in a fusion of the 2 genes with
expression of a chimeric EWSR1-WT1 product. The most common breakpoints involve the intron
between EWSR1 exon 7 and 8 and the intron between WT1 exons 7 and 8. Analyses of these transcripts
have shown an in-frame fusion of RNA encoding the amino-terminal domain of EWSR1 to the zinc finger
of the DNA-binding domain of WT1.
Useful For: Supporting the diagnosis of desmoplastic small-round-cell tumor
Interpretation: A positive result for EWSR1-WT1 is consistent with a diagnosis of desmoplastic
small-round-cell tumor (DSRCT). Sarcomas other than DSRCT, and carcinomas, melanomas, and
lymphomas are negative for the fusion products. A negative result does not rule out a diagnosis of
DSRCT.
Reference Values:
Negative
Clinical References: 1. Barr FG, Chatten J, D'Cruz CM, et al: Molecular assays for chromosomal
translocations in the diagnosis of pediatric soft tissue sarcomas. JAMA 1995;273:553-557 2. Gerald WL,
Miller HK, Battifora H, et al: Intra-abdominal desmoplastic small round-cell tumor: Report of 19 cases of
a distinctive type of high-grade polyphenotypic malignancy affecting young individuals. Am J Surg
Pathol 1991;15:499-513 3. Gerald WL, Rosai J, Ladanyi M: Characterization of the genomic breakpoint
and chimeric transcripts in the EWS-WT1 gene fusion of demoplastic, small round-cell tumor. Proc Natl
Acad Sci USA 1995;92:1028-1032 4. Jin L, Majerus J, Oliveira A, et al: Detection of fusion gene
transcripts in fresh-frozen and formalin-fixed paraffin-embedded tissue sections of soft tissue sarcomas
after laser capture microdissection and RT-PCR. Diagn Mol Pathol 2003;12:224-230
Dexamethasone
Reference Values:
Dexamethasone, Serum* ng/dL
Adults baseline: