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Test ID TRK Tropomyosin Receptor Kinase (TRK) Immunostain, Technical Component Only

Ordering Guidance

This test includes only technical performance of the stain (no pathologist interpretation is performed). If diagnostic consultation by a pathologist is required order PATHC / Pathology Consultation.

Shipping Instructions

Attach the green pathology address label and the pink Immunostain Technical Only label included in the kit to the outside of the transport container.

Specimen Required

Supplies: Immunostain Technical Only Envelope (T693)

Specimen Type: Tissue

Preferred: 2 Unstained positively charged glass slide (25- x 75- x 1-mm) per test ordered; sections 4-microns thick.

Acceptable: Formalin-fixed, paraffin-embedded (FFPE) tissue block


If not ordering electronically, complete, print, and send 1 of the following forms with the specimen:

Immunohistochemical (IHC)/In Situ Hybridization (ISH) Stains Request

Oncology Test Request (T729)

Useful For

Helpful in the screening for neurotrophic tyrosine receptor kinase (NTRK) rearranged tumors

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
IHTOI IHC Initial, Tech Only No No
IHTOA IHC Additional, Tech Only No No

Method Name


Reporting Name

TRK IHC, Tech Only

Specimen Type


Specimen Stability Information

Specimen Type Temperature Time Special Container
TECHONLY Ambient (preferred)

Clinical Information

Neurotrophic tyrosine receptor kinase (NTRK) is a family of 3 proto-oncogenes including NTRK1, NTRK2, and NTRK3 which encode TRKA, TRKB, and TRKC proteins. Tropomyosin receptor kinase (TRK) immunohistochemistry may be used as a screen for identifying NTRK rearrangements and may be particularly helpful in driver-negative advanced malignancies such as secretory carcinoma, congenital infantile fibrosarcoma and lipofibromatosis-like neural tumors. Screening for NTRK rearranged tumors is important as patients have been shown to respond to TRK inhibitor therapy.


This test includes only technical performance of the stain (no pathologist interpretation is performed). If diagnostic consultation by a pathologist is required order PATHC / Pathology Consultation.


The positive and negative controls are verified as showing appropriate immunoreactivity. If a control tissue is not included on the slide, a scanned image of the relevant quality control tissue is available upon request. Contact 855-516-8404.


Interpretation of this test should be performed in the context of the patient's clinical history and other diagnostic tests by a qualified pathologist.

Clinical Reference

1. Hung YP, Fletcher CDM, and Hornick JL: Evaluation of Pan-TRK Immunohistochemistry in Infantile Fibrosarcoma, Lipofibromatosis-like Neural Tumor, and Histologic Mimics. Histopathology 2018; doi: 10.1111/his.13666

2. Davis JL, Lockwood CM, Albert CM et al: Infantile NTRK-associated Mesenchymal Tumors. Pediatric and Developmental Pathology 2018;21(1) 68-78

3. Drilon S, Laetsch TW,  Kummar S et al: Efficacy of Larotrectinib in TRK Fusion-Positive Cancers in Adults and Children. N Engl J Med 2018;378:731-739

4. Hechtman JF, Benayed R, Hyman DM et al: Pan-Trk Immunohistochemistry is an Efficient and Reliable Screen for the Detection of NTRK Fusions. Am J Surg Pathol 2017;41(11):1547-1551

5. Agaram NP, Zhang L, Sung YS, et al: Recurrent NTRK1 gene fusions define a novel subset of locally aggressive Lipofibromatosis-like neural tumors. Am J Surg Pathol 2016;40:1407-1416

Day(s) Performed

Monday through Friday

Report Available

1 to 3 days

Test Classification

This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information

88342-TC, primary

88341-TC, if additional IHC

LOINC Code Information

Test ID Test Order Name Order LOINC Value
TRK TRK IHC, Tech Only Order only;no result


Result ID Test Result Name Result LOINC Value
603301 TRK IHC, Tech Only Bill only; no result
Mayo Clinic Laboratories | IHC Catalog Additional Information: