Ordering Recommendation

Aid in prediction of response to HER2-directed therapy in patients with breast carcinoma or gastroesophageal adenocarcinoma. Use to confirm equivocal HercepTest (2+) immunohistochemistry (IHC) result.




Fluorescence in situ Hybridization (FISH)




3-9 days

New York DOH Approval Status

This test is New York DOH approved.

Specimen Required

Patient Preparation

Tumor tissue.

Specimen Preparation

Formalin fix (10 percent neutral buffered formalin) and paraffin-embed tissue. Fixative duration: 6-72 hours.  Protect paraffin block from excessive heat. Transport block or 7 unstained (4 micron thick sections) positively charged slides in a tissue transport kit (ARUP supply #47808) available online through eSupply using ARUP Connect™ or contact ARUP Client Services at (800) 522-2787 (kit recommended but not necessary). (Min 4 slides)

Storage/Transport Temperature

Room temperature. Also acceptable: Refrigerated. Ship in cooled container during summer months.

Unacceptable Conditions

Specimens fixed or processed in alternative fixatives (alcohol, Prefer) or heavy metal fixatives (B-4 or B-5). No tumor in tissue. Decalcified specimens.  Tissue fixed for less than 6 hours or greater than 72 hours.


Include surgical pathology report.
If multiple specimens (blocks or slides) are sent to ARUP, they must be accompanied by one of the following: an order comment indicating that the ARUP pathologist should choose the specimen most appropriate for testing (e.g., "Choose best block"), or individual orders for each sample submitted. A Pathologist Block Selection Fee (ARUP test code 3002076) will be added to orders that utilize the first option. If multiple specimens are sent to ARUP without a request for pathologist block/slide selection or individual orders, they will be held until clarification is provided.


Ambient: Indefinitely; Refrigerated: Indefinitely; Frozen: Unacceptable

Reference Interval

Interpretive Data

Refer to report. ARUP uses the most recent ASCO/CAP interpretation criteria for evaluating ERBB2 (HER2) status.

Compliance Category



Breast tissue results of FISH group 2, 3, or 4 will be reflexed to ERBB2 (HER2/neu) (HercepTest) with Interpretation by Immunohistochemistry, Tissue (ARUP test code 0049174). Additional charges apply. Gastric and other non-breast tissue with indeterminate results will be reflexed to an alternate probe in an effort to resolve amplification status. Additional charges apply.

Hotline History


CPT Codes

88377, if reflexed add 88360 or 88377


Component Test Code* Component Chart Name LOINC
0049241 ERBB2 (HER2) by FISH 42783-1
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.


  • c-erbB2 FISH
  • CEP17
  • HER-2/neu FISH
  • Her-2/neu Gene Amplification or Overexpression
  • HER2/CEP17 Ratio
ERBB2 (HER2/neu) Gene Amplification by FISH with Reflex, Tissue