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Immunohistochemistry (IHC)
Test Description
ROS1 gene rearrangements are reported in 1% to 2% of lung adenocarcinomas and are associated with a response to the multi-targeted tyrosine kinase inhibitor crizotinib. ROS1 rearrangement can be detected by using IHC for ROS1 protein as an alternate screening test. We recommend that any positive results be confirmed by ROS FISH studies.
Specimen Requirements
  • A formalin-fixed, paraffin-embedded (FFPE) tissue block is preferred specimen type


  • One (1) unbaked, unstained slide for H&E staining (required) and two to three (2-3) positively charged unstained slides (all cut at 4-5 microns) for each test/antibody ordered

  • Block and slide identifiers should be clearly written and match exactly with the specimen ID and specimen labeling as noted on the requisition.

Storage and Transportation
Use cold pack for transport. Make sure cold pack is not in direct contact with specimen.
CPT Code(s)*
88342 x 1 or 88341 x 1
Turnaround Time
Global: 48 hours, Tech-Only (stain only): 24 hours
New York Approved
Level of Service
Stain Only

*The CPT codes provided with our test descriptions are based on AMA guidelines and are for informational purposes only. Correct CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed.