October 18, 2023
A tumour capsule is a thin tissue layer separating a tumour from the surrounding normal tissue. Both benign (non-cancerous) and malignant (cancerous) tumours may have a capsule. Tumours surrounded by a capsule are described as being encapsulated, while tumours that do not have a capsule are described as non-encapsulated.
What does capsule invasion mean?
Pathologists use the term tumour capsule invasion or capsular invasion to describe tumour cells that have broken through the capsule and spread into the surrounding normal tissue (the spread of tumour cells into normal tissue is called invasion). In some parts of the body, capsule invasion is used to distinguish between benign (noncancerous) and malignant (cancerous) tumours made up of very similar-looking cells. For example, follicular adenoma and minimally invasive follicular carcinoma are similar-looking thyroid gland tumours. However, follicular adenoma is a benign tumour, while minimally invasive follicular carcinoma is malignant. A capsule also surrounds both tumours. The most important difference is that the minimally invasive follicular carcinoma cells show capsule invasion, while those in follicular adenoma do not.
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Doctors wrote this article to help you read and understand your pathology report. Contact us if you have questions about this article or your pathology report.
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