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Alternative Name
Insulinoma-associated protein 1
Immunohistochemistry (IHC)
Test Description

INSM1 is a transcription factor that is a sensitive and specific marker for neuroendocrine tumors.  It is a nuclear stain, and is as good if not better than synaptophysin and is superior to chromogranin. It is rarely expressed on adenocarcinoma or squamous cell carcinomas without neuroendocrine differentiation. 

Specimen Requirements
  • A formalin-fixed, paraffin-embedded (FFPE) tissue block is preferred specimen type
  • or
  • 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

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.