Hurthle cell adenoma

by Jason Wasserman MD PhD FRCPC
June 14, 2022


About this article: This article was created by doctors to help you read and understand your pathology report for Hurthle cell adenoma. If you have any questions about this article or your pathology report, please contact us.

What is a Hurthle cell adenoma?

A Hurthle cell adenoma is a non-cancerous type of thyroid tumour. It is made up of large pink cells called Hurthle cells that are separated from the normal thyroid tissue by a thin tissue barrier called a tumour capsule. The tumour often forms a lump in the thyroid gland called a nodule.

How is the diagnosis of Hurthle cell adenoma made?

The diagnosis of Hurthle cell adenoma can only be made after the entire tumour is removed and sent to a pathologist for examination under the microscope. However, most patients undergo a minor surgical procedure called a fine needle aspiration or FNA before the tumour is removed completely. This procedure uses a very thin needle to remove a small amount of tissue from the abnormal area of the thyroid gland. This tissue is then examined by a pathologist under the microscope. The FNA biopsy provides a preliminary diagnosis that helps guide further management.

Hurthle cells

What does Hurthel cell adenoma look like under the microscope?

Hurthle cell adenoma is made up of large pink Hurthle cells. The Hurthle cells are typically arranged in small to medium-sized follicles. When viewed under the microscope, the cells in a Hurthle cell adenoma can look very similar to the cells in a type of thyroid cancer called Hurthle cell carcinoma. The only difference between a Hurthle cell adenoma and a Hurthle cell carcinoma is that all of the abnormal cells in a Hurthle cell adenoma are separated from the normal thyroid gland by a thin tissue barrier called a tumour capsule. In contrast, in a Hurthle cell carcinoma, the tumour cells have broken through the tumour capsule and have entered the surrounding normal thyroid gland. Pathologists describe this as tumour capsule invasion. For this reason, the diagnosis of Hurthle cell adenoma can only be made after the tumour has been removed completely. By examining the entire tumour capsule, your pathologist can make sure that there is no evidence of tumour capsule invasion.

Hurthle cell adenoma

Hurthle cell carcinoma

Post biopsy changes

The FNA performed before the tumour is removed fully causes changes in the thyroid gland and the tumour that can be seen under the microscope. Your pathology report may describe these changes as post-biopsy changes or FNA-like changes.

These changes include hemorrhage (bleeding), cystic degeneration (the development of holes or spaces in the tissue), and atypical (abnormal) looking cells. All of these changes are expected non-cancerous findings in a Hurthle cell adenoma.

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