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Test ID TTF40 TTF41 (SPT24) + p40 Immunostain, Technical Component Only

Shipping Instructions

Attach the green pathology address label and the pink Immunostains 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: Immunostains Technical Only Envelope (T693)

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

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

Useful For

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


p40 aids in the classification of carcinomas and lymphomas

Reflex Tests

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

Method Name


Reporting Name

TTF1 (SPT24) + p40 IHC, Tech Only

Specimen Type


Specimen Stability Information

Specimen Type Temperature Time Special Container
TECHONLY Ambient (preferred)

Clinical Information

Thyroid transcription factor 1 (TTF1) is a nuclear protein (detected by the chromogen 3,3'-diaminobenzidine: DAB) expressed in thyroid follicular cells, type II pneumocytes, and a subset of bronchial cells. The p40 antibody recognizes the deltaNp63 isoform of p63 (detected by the chromogen fast red). The predominant localization of p40 is in the basal layer of the stratified squamous and transitional epithelia. Given the relative specificity of TTF1 for cells of thyroid or lung origin, TTF1 is often included in a panel to identify the primary site for carcinomas of unknown origin. The p40 antibody may help to distinguish squamous cell carcinomas from other non-small cell carcinomas.


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. Pelosi G, Fabbri A, Tamborini E, et al: Challenging Lung Carcinoma with Coexistent ?Np63/p40 and Thyroid Transcription Factor-1 Labeling Within the Same Individual Tumor Cells. J Thorac Oncol 2015 Oct;10(10):1500-1502

2. Whithaus K, Fukuoka J, Prihoda TJ, et al: Evaluation of napsin A, cytokeratin 5/6, p63, and thyroid transcription factor 1 in adenocarcinoma versus squamous cell carcinoma of the lung. Arch Pathol Lab Med 2012 Feb;136(2):155-162

3. Sterlacci W, Savic S, Schmid T, et al: Tissue-Sparing Application of the Newly Proposed IASLC/ATS/ERS Classification of Adenocarcinoma of the Lung Shows Practical Diagnostic and Prognostic Impact. AJCP 2012;137:946-956

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


LOINC Code Information

Test ID Test Order Name Order LOINC Value
TTF40 TTF1 (SPT24) + p40 IHC, Tech Only Order only;no result


Result ID Test Result Name Result LOINC Value
602648 TTF1 (SPT24) + p40 IHC, Tech Only Bill only; no result


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

Mayo Clinic Laboratories | IHC Catalog Additional Information: