Topic Completed: 1 June 2005

Revised: 11 March 2019

Copyright: 2003-2018,, Inc.

PubMed Search: TTF1
Page views in 2018: 21,397
Page views in 2019 to date: 7,507
Cite this page: Pernick N. TTF1. website. Accessed April 24th, 2019.
Definition / general
  • Thyroid transcription factor, also called thyroid specific enhancer binding protein
  • 38 kDa nuclear protein that regulates transcription activity of thyroid (thyroglobulin, thyroperoxidase, sodium-iodide transport protein, calcitonin and MHC class I), lung (surfactant proteins A, B and C, Clara cell secretory protein) and diencephalon specific genes
  • Mutations cause pulmonary hypoplasia and neonatal death
  • Specificity depends on antibody clone used
  • Interpretation: nuclear stain
Uses by pathologists
  • Distinguish primary (TTF1+) vs. metastatic (usually TTF1-) lung carcinoma
  • Distinguish pulmonary adenocarcinoma (TTF1+) from squamous cell carcinoma (usually TTF1-)
  • Pleural lung carcinoma (TTF1+) vs. mesothelioma (TTF1-)
  • Pulmonary small cell carcinoma (TTF1+) vs. Merkel cell carcinoma (TTF1-)
Microscopic (histologic) images

Images hosted on PathOut server:

Contributed by Andrey Bychkov, M.D., Ph.D.:

Expression by follicular epithelium

Papillary thyroid carcinoma, TTF1

Images hosted on other servers:

Pulmonary adenocarcinoma
metastasis (left) to
renal cell carcinoma (right)
CK7 (2A); TTF1+ (2B); RCC (2C)

Positive staining - normal
  • Lung type II pneumocytes and Clara cells; thyroid follicular and parafollicular C cells
Positive staining - disease
Negative staining
  • Merkel cell carcinoma of skin, most nonpulmonary non-small cell carcinomas
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