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Test Code TTFK5 Thyroid Transcription Factor 1 (TTF1) (SPT24) and Keratin 5 (KRT5) 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 "Attention Pathology" address label (T498) and the pink Immunostain Technical Only label included in the kit to the outside of the transport container.



Specimen Required


Specimen Type: Tissue

Supplies: Immunostain Technical Only Envelope (T693)

Container/Tube: Immunostain Technical Only Envelope

Preferred:

-Formalin-fixed, paraffin-embedded tissue block

OR

-2 Unstained, positively charged glass slides (25- x 75- x 1-mm) per test ordered; sections 4-microns thick

Acceptable: None


Useful For

Thyroid transcription factor 1aids in the classification of carcinomas of unknown origin

 

Keratin 5 aids in the identification of squamous cell carcinoma

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
IHMTO IHC Multiplex, Tech Only No No

Method Name

Immunohistochemistry (IHC)

Reporting Name

TTF1(SPT24) + KRT5 IHC, Tech Only

Specimen Type

TECHONLY

Specimen Stability Information

Specimen Type Temperature Time Special Container
TECHONLY Ambient (preferred)
  Refrigerated 

Reject Due To

Wet/frozen tissue
Cytology smears
Nonformalin fixed tissue
Nonparaffin embedded tissue
Noncharged slides
ProbeOn slides
Snowcoat slides		 Reject

Clinical Information

Thyroid transcription factor 1 (TTF1) is a nuclear protein (detected by the chromogen 3,3'-diaminobenzidine) expressed in thyroid follicular cells, type II pneumocytes, and a subset of bronchial cells. Keratin 5 is a type II cytokeratin (detected by the chromogen fast red) that dimerizes with the type I cytokeratin 14 forming intermediate filaments in the basal layer of the epidermis. Keratin 5 is useful for differentiating squamous cell carcinoma (KRT5 positive) from pulmonary adenocarcinomas (KRT5 negative). This immunostain is often included in a panel to identify the primary site for carcinomas of unknown origin.

Interpretation

This test does not include pathologist interpretation, only technical performance of the stain. If interpretation is required, order PATHC / Pathology Consultation for a full diagnostic evaluation or second opinion of the case.

 

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; call 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.

Cautions

Age of a cut paraffin section can affect immunoreactivity. Stability thresholds vary widely among published literature and are antigen dependent. Best practice is for paraffin sections to be cut within 6 weeks.

 

The charge of glass slides can be affected by environmental factors and subsequently may alter slide staining. Sending unsuitable glass slides can result in inconsistent staining due to poor slide surface chemistry.

 

Best practices for storage of positively charged slides:

-Minimize time slides are stored after being unpackaged

-Limit exposure to high humidity and heat

-Minimize exposure to plastics

Day(s) Performed

Monday through Friday

Report Available

1 to 3 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

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

88344-TC

LOINC Code Information

Test ID Test Order Name Order LOINC Value
TTFK5 TTF1(SPT24) + KRT5 IHC, Tech Only Order only;no result

 

Result ID Test Result Name Result LOINC Value
70801 TTF1(SPT24) + KRT5 IHC, Tech Only Bill only; no result

Forms

If not ordering electronically, complete, print, and send a Immunohistochemical (IHC)/In Situ Hybridization (ISH) Stains Request (T763) with the specimen.