April 13, 2023

TTF-1 (stands for thyroid transcription factor -1) is a protein made by cells normally found in the thyroid gland, lungs, thymus, and brain. Most benign (noncancerous) and malignant (cancerous) tumours that start from cells in these organs also make this protein. Normal neuroendocrine cells and tumours made up of neuroendocrine cells can also make TTF-1.

Pathologists perform a test called immunohistochemistry (IHC) to identify cells making 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.

Examples of benign (noncancerous) tumours that are positive for TTF-1:
Examples of malignant (cancerous) tumours that are positive for TTF-1:

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This article was written by doctors to help you read and understand your pathology report. Contact us if you have a question about this article or your pathology report.

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