Mayo Test Catalog, (Sorted By Test Name) - Mayo Medical ...

83365
FDXM
91956
1):167-170 2. Amagai M, Komai A, Hashimoto T, et al: Usefulness of enzyme linked immunoabsorbent
assay using recombinant desmogleins 1 and 3 for sero-diagnosis of pemphigus. Brit J Dermatol 1999
Feb;140(2):351-357 3. Harman KE, Gratin MJ, Bhogal SJ, et al: The clinical significance of
autoantibodies to desmoglein 1 in 78 cases of pemphigus vulgaris. J Invest Derm 1999;115:568
Desmoplastic Small Round Cell Tumor (DSRCT) by Reverse
Transcriptase PCR (RT-PCR), Paraffin
Clinical Information: Desmoplastic small-round-cell tumor (DSRCT) is a member of the
small-round-cell tumor group that also includes rhabdomyosarcoma, synovial sarcoma, lymphoma, Wilms
tumor, and Ewing sarcoma. DSRCT is a type of sarcoma that affects mainly children and adolescent
males, usually in the form of widespread intra-abdominal growth not related to any specific organ system.
The tumor is composed of angulated nests of small round cells with an abundant desmoplastic stroma.
The tumor cells show multiphenotypic differentiation and are usually positive for cytokeratin and
desmin.(1-4) These tumors can express renal, epithelial, muscle, and endocrine markers. While treatment
and prognosis depend on establishing the correct diagnosis, the diagnosis of sarcomas that form the
small-round-cell tumor group can be very difficult by light microscopic examination alone, especially true
when only small needle-biopsy specimens are available for examination. The use of histochemical and
immunohistochemical stains (eg, desmin, cytokeratin, and WT1) can assist in establishing the correct
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
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