FISH Study: Neoplastic Interphase EWSR1

CPT Code(s):

  • 88271
  • 88275
  • 88291


Interphase nuclei fluorescence in-situ hybridization (FISH) fusion rearrangement analyses; a concurrent or previous conventional cytogenetic workup is required/recommended (where possible).


Monday - Saturday


5 - 12 days


This test is used to detect the presence of rearrangements involving the EWSR1 gene locus at 22q11.2 in non-preserved/fixed tissue specimens, which have been described in several types of soft tissue neoplasms, including Ewing sarcoma, PNET, clear cell sarcoma and extraskeletal myxoid chondrosarcoma.

Specimen Requirements:

  • Bone Marrow Aspirate: Obtain 1 - 2 cc of in a green-top sodium heparin tube and immediately rotate it thoroughly to ensure adequate mixing with the anticoagulant.
  • Bone Marrow Core Biopsy: Deposit samples in a sterile container containing tissue culture medium with antibiotics (RPMI) that have been brought to room temperature before collection.*
  • Peripheral Blood Specimens: Peripheral blood specimens may be submitted in those clinical conditions (e.g. circulating blasts).
  • Unacceptable Conditions:
    • Frozen specimens
    • Specimens for FISH study only greater than one week old
    • Specimens for concurrent FISH and cytogenetic studies greater than 48 hours old*
    • Formalin, alcohol or paraffin-preserved specimens
  • Stability (collection to initiation of testing):
    • Ambient: 24 - 48 hours*
    • Frozen: Unacceptable

* Cell viability of specimens requiring cell culture may be compromised in specimens more than 48 hours old upon receipt. Refrigeration at 2° - 8° C may assist when a delay is not preventable. Do not freeze or place specimens directly on ice.

Collection Procedure:


Reference Values:

By report; interpretive

Interpretation Data:



UFHPL Test #: 30170

Reported Notes: