Fluorescence In Situ Hybridization (FISH)
DDIT3 (formerly CHOP) encodes a transcription factor involved in adipogenesis and erythropoiesis. Rearrangements involving this gene are characteristic of myxoid liposarcoma. Morphologically, myxoid liposarcomas demonstrates uniform, small spindled cells within a myxoid stroma with distinctive arborizing capillaries. A subset of myxoid liposarsomas show progression to round cell morphology, associated with a poorer prognosis. Approximately 95% of myxoid liposarcomas bear a t(12;16)(q13;p11) rearrangement that results in the fusion of the N-terminal transactivation domain of FUS and the full length of DDIT3. In the remaining cases, there is a similar rearrangement involving DDIT3 and EWSR1. The detection of DDIT3 rearrangements can be useful in diagnosing myxoid liposarcoma – including uncommon histologic variants – and in distinguishing this sarcoma from other mesenchymal tumors that may be considered in the differential diagnosis.
This test will detect rearrangements involving DDIT3 but will not identify the translocation partner.
3 – 10 days
A formalin-fixed, paraffin-embedded tissue block (containing sufficient neoplastic cells) is preferred. Unstained slides (3 slides cut at 4-microns) with associated H&E-stained slide are also acceptable. Decalcified tissue or tissues with other fixatives will be accepted and the assay attempted; however, these specimens may result in failed testing due to degraded nucleic acid. Both blocks and slides should be stored at room temperature.
By ordering this test the clinician acknowledges that informed consent has been obtained from the patient as required by applicable state or federal laws and the ordering clinician has authorization from the patient permitting MLabs to report the test results to the ordering clinician. Test includes pathologist interpretation of results billed as a separate additional charge. This test is not available without interpretation.