c-KIT Mutations with Reflex to PDGFRA Mutations for GIST

Test Code

16237

CPT Codes
81272

Includes

If c-KIT Mutation, Cell-based result is Not detected, then PDGFRA Mutation Analysis will be performed at an additional charge (CPT code(s): 81314).

Preferred Specimen

Formalin-fixed paraffin embedded tissue

Minimum Volume

1 mL bone marrow
4 mL whole blood

Other Acceptable Specimens

3 mL bone marrow collected in an EDTA (lavender-top) tube • 6 mL whole blood collected in an EDTA (lavender-top) tube

Instructions

Collect 6 mL of whole blood or 3 mL bone marrow in lavender-top (EDTA) tube. Whole blood or bone marrow is shipped refrigerated. Do not freeze whole blood or bone marrow. After collection of the sample, draw date and time, as well as sample type, must be written on the tube and included as requested information.

Transport Temperature

Formalin fixed paraffin embedded tissue: Room temperature
Bone marrow and whole blood: Refrigerated (cold packs)

Specimen Stability

Tissue
Room temperature: Indefinite
Refrigerated: Indefinite
Frozen: Unacceptable

Bone marrow and whole blood
Room temperature: 7 days
Refrigerated: 14 days
Frozen: Unacceptable

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Gross hemolysis • Clotted or frozen whole blood • Clotted or frozen bone marrow

Methodology
Next Generation Sequencing

FDA Status
This test was developed and its analytical performance characteristics have been determined by Quest Diagnostics. It has not been cleared or approved by FDA. This assay has been validated pursuant to the CLIA regulations and is used for clinical purposes.

Setup Schedule

A.M. Sets up 1 day a week.

Clinical Significance

Eighty percent of patients with gastrointestinal stromal tumor (GIST) have a C-KIT mutation in exon 9, 11, 13, or 17. The presence of a mutation usually predicts poor survival. Patients with C-KIT mutations other than D816V are likely to respond to imatinib (Gleevec) therapy. Mutations in the PDGFRA gene are found in about 7% of gastrointestinal stromal tumors (GISTs), especially in KIT wild type GISTs. PDGFRA mutations also have been described in synovial sarcomas (SSs) and malignant peripheral nerve sheath tumors (MPNST). GISTs with PDGFRA mutations (except D842V) are likely to respond to imatinib.

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.