FISH for HER-2

Test Mnemonic


CPT Codes

  • 88377 - QTY (1)


  • Breast Cancer (HER2/ERBB2) Gene Amplification
  • FISH for HER2 (ERBB2)


  • LSI 17p11

Performing Laboratory

Cleveland Clinic Laboratories

Specimen Requirements

Volume Type Container Collect Temperature Transport Temperature Special Instructions
2 slidesSlide (s), unstainedClean containerN/AAmbientOne formalin-fixed, paraffin embedded block containing representative tissue OR unstained 4 μm tissue sections on electrostatically charged slides containing representative tumor. Tissue must be fixed in formalin NOT B5 or PREFER fixative IHC data must be included when ordering HER2 FISH testing.


Environmental Condition Description
AmbientSample is formalin fixed and must not be fixed in Prefer or B5

Days Performed

5 days per week

Turnaround Time

5 - 7 days


Name Description
Fluorescent In-Situ Hybridization (FISH) 

Reference Range

Special Info

Breast cancer tissue: primary or metastatic. IHC data must be included when ordering HER2 FISH testing. Please note: based on the 2018 Focused Update to the ASCO/CAP guidelines for human epidermal growth factor receptor 2 testing in breast cancer (PMID:29846104), reflex testing using immunohistochemistry will be performed when the HER2 (ERBB2) FISH result is Group 2, 3, or 4. For these cases, the TAT will be extended by 3-4 days.

Clinical Info

Interphase FISH analysis utilizing an enumeration probe for the ERBB2 (HER2) gene at 17q12, as well as a probe specific to the centromere of chromosome 17. Used to detect amplification of the ERBB2 (HER2) gene in human breast tissue specimens, and other tumors, both primary and metastatic. If no cells are available for analysis, no analysis charges will be incurred.

Clinical Limitation

This assay has not been validated n decalcified tissues. Results should be interpreted with caution given the likelihood of false negativity on decalcified specimens. This assay is not validated for primary gastric tumors.