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

TFE3
61013
alone, especially true when only small-needle biopsy specimens are available for examination. The use
of immunohistochemical stains (eg, desmin, actin, and the nuclear transcription factor markers MyoD
and myogenin) are useful in separating rhabdomyosarcomas from other small-round-cell tumors, but do
not always distinguish the various subtypes of rhabdomyosarcomas. 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) Most cases
of ARMS have a t(2;13)(q35;q14) reciprocal translocation. This rearrangement juxtaposes 5' portions of
the PAX3 gene on chromosome 2 with 3' portion of the FOXO1A gene on chromosome 13 resulting in
a chimeric gene in the designated chromosome 13 that encodes a transcriptional regulatory protein in
75% of cases.(1) Another variant t(1;13)(q36;q14) translocation fuses the 5' portion of the PAX7 gene
on chromosome 1 with the FOXO1A gene on chromosome 13 in a smaller number of cases (10%). The
PAX3-FOXO1A fusion is associated with a worse prognosis than the PAX7-FOXO1A fusion.
Useful For: Supporting the diagnosis of alveolar rhabdomyosarcoma
Interpretation: A positive result is consistent with a diagnosis of alveolar rhabdomyosarcoma
(ARMS). Sarcomas other than ARMS, and carcinomas, melanomas, and lymphomas are negative for the
fusion products. A negative result does not rule-out a diagnosis of ARMS.
Reference Values:
Negative
Clinical References: 1. Edwards RH, Chatten J, Xiong QB, Barr FG: Detection of gene fusions in
rhabdomyosarcoma by reverse transcriptase polymerase chain reaction assay of archival samples. Diagn
Mol Pathol 1997;6:91-97 2. Ladanyi M, Bridge JA: Contribution of molecular genetic data to the
classification of sarcomas. Hum Pathol 2000;31:532-538 3. Galili N, Davis RJ, Fredricks WJ, et al:
Fusion of a fork head domain gene to PAX3 in the solid tumor alveolar rhabdomyosarcoma. Nat Genet
1993;5:230-235 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
Alveolar Soft Part Sarcoma (ASPS)/Renal Cell Carcinoma
(RCC), Xp11.23 (TFE3), FISH, Tissue
Clinical Information: Alveolar soft-part sarcoma (ASPS) is a rare malignant tumor typically
occurring in patients in their 20s to 30s within the muscle and deep tissues of the extremities. ASPS is
slow growing and refractory to chemotherapy with a propensity to metastasize. Prolonged survival is
possible even with metastasis, although the long-term disease-related mortality rate is high. ASPS is
characterized by a translocation that results in fusion of TFE3 on chromosome Xp11.2 with ASPSCR1
(also called ASPL or RCC17) on chromosome 17q25.3.(1,2) Both balanced and unbalanced forms (loss of
the derivative X chromosome) of the translocation have been observed.(2,3) Another tumor, a rare subset
of papillary renal cell carcinoma (RCC) with a distinctive pathologic morphology, has rearrangements of
TFE3 with ASPSCR1 or other fusion partner genes.(1,4,5) This tumor predominantly affects children and
young adults, presents at an advanced stage but with an indolent clinical course, and is a distinct entity in
the World Health Organization classification.(6) Typically a balanced form of the translocation is present
in the RCC variant. An assay to detect rearrangement of TFE3 is useful to resolve diagnostic uncertainty
in these tumor types, as immunohistochemistry for TFE3 is not reliable.
Useful For: Aids in the diagnosis of alveolar soft-part sarcoma or renal cell carcinoma variant when
used in conjunction with an anatomic pathology consultation
Interpretation: A neoplastic clone is detected when the percent of nuclei with the abnormality exceeds
the established normal cutoff for the TFE3 probe set. A positive result of TFE3 rearrangement is
consistent with a diagnosis of alveolar soft-part sarcoma (ASPS) or renal cell carcinoma (RCC) variant. A
negative result suggests that TFE3 is not rearranged, but does not exclude the diagnosis of ASPS or RCC
variant.
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