TTF-1

MyPathologyReport
April 13, 2023

TTF-1 (stands for thyroid transcription factor -1) is a transcription factor that plays an important role in the development and differentiation of the thyroid gland, thymus, lung, and brain. It is a nuclear protein which means it is normally found in a part of the cell called the nucleus.

TTF-1 is normally expressed in the following cell types:

• Thyroid follicular cells: These cells produce thyroid hormones and are essential for thyroid gland function.
• Respiratory epithelial cells: These include alveolar type II cells and Clara cells in the lungs, which are involved in surfactant production and respiratory epithelial maintenance.
• Neuroendocrine cells: These cells are found throughout the body. They have both neural and endocrine functions.

Tumours that express TTF-1

Noncancerous tumors

• Pulmonary hamartomas: Benign lung tumors made up of cartilage, fat, and connective tissue.
• Thyroid adenomas: Benign tumors of the thyroid gland including follicular adenoma and oncocytic adenoma.

Cancerous tumours

• Lung cancer: Types of lung cancer that express TTF-1 include adenocarcinoma, adenosquamous carcinoma, and small cell carcinoma.
• Thyroid cancer: Most types of thyroid cancer including papillary thyroid carcinoma, follicular carcinoma, oncocytic carcinoma, and medullary carcinoma express TTF-1.
• Neuroendocrine tumours: Most neuroendocrine tumours including well differentiated neuroendocrine tumour and neuroendocrine carcinoma express TTF-1.

How do pathologists test for TTF-1?

Pathologists perform immunohistochemistry (IHC) to identify cells expressing TTF-1. This test is helpful when trying to determine if the cells in a tumour came from the thyroid gland, lung, thymus, or brain. The protein is normally found in a part of the cell called the nucleus. When interpreting an IHC test, pathologists describe cells that are making TTF-1 as positive and those that are not as negative.

About this article

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Other helpful resources

Atlas of Pathology