Hurthle cells

# Overview
Hurthle cells are also called Askanazy cells. They are the specific cells found in the thyroid gland and are visible on the histopathological picture. Hurthle cells have eosinophilic cytoplasm and are abundant in mitochondria. They may be present in a variety of thyroid diseases including Hashimoto's thyroiditis and thyroid carcinoma (Hurthle cel carcinoma; A subtype of follicular thyroid cancer).

# Hurthle cells
Hurthle cells are also called Askanazy cells. They are the specific cells found in the thyroid gland and are visible on the histopathological picture. Hurthle cells have eosinophilic cytoplasm and are abundant in mitochondria. They may be present in a variety of thyroid diseases including Hashimoto's thyroiditis and thyroid carcinoma (Hurthle cel carcinoma; A subtype of follicular thyroid cancer).

## History
The Hurthle cell is named after German histologist Karl Hurthle, who investigated thyroid secretory function, particularly in dogs. The cell known as the Hurthle cell was first described in 1898 by Max Askanazy, who noted it in patients with Graves' disease. Oncocytes in the thyroid are often called Hurthle cells. Although the terms oncocyte, oxyphilic cell, and Hurthle cell are used interchangeably, Hurthle cell is used only to indicate cells of thyroid follicular origin.

## Microscopic Histology
Hurthle cells are also called Askanazy cells. They are the specific cells found in the thyroid gland and are visible on the histopathological picture. They may be present in a variety of thyroid diseases including Hashimoto's thyroiditis and thyroid carcinoma.
These cells are characterized by the following:
- Large, polygonal cells
- Eosinophilic cytoplasm
- Abundance of mitochondria

## Significance of Hurthle cells
Hurthle cells are present in the following conditions:
- Hashimoto's thyroiditis
- Grave's disease
- Benign thyroid adenomas
- Follicular thyroid carcinoma

## Diagnosis
Hurthle cell adenomas are more frequent than Hurthle cell carcinomas. It is difficult to differentiate between being benign or malignant Hurthle cell lesions. Chronic lymphocytic thyroiditis or Hashimoto's thyroiditis, along with cases of long-standing Graves' disease, show Hurthle cells present. Classification is important since widely invasive tumors can have outcomes with a 55% mortality rate. Hurthle cell carcinomas consist of at least 75% Hurthle cells.
- Size and growth pattern of the tumor cannot be used to determine malignancy, although larger tumors have a higher incidence of malignancy, Hurthle cell adenomas and carcinomas are differentiated on the basis of capsular and vascular invasion.
- Tumors displaying only capsular invasion tend to behave less aggressively than those with vascular invasion.
- Hurthle cell carcinomas are characterized as either minimally invasive or widely invasive tumors.
- The minimally invasive or encapsulated carcinoma is fully surrounded by a fibrous capsule.
- The widely invasive carcinoma shows an extensive area of both capsular and vascular invasion with the leftover capsule typically difficult to identify.

## Treatment
The appropriate diagnosis of the underlying cause of the Hurthle cells in the histological picture directs the treatment.
- Grave's disease and Hashimoto's thyroiditis are usually treated for hyperthyroidism and hypothyroidism respectively.
- A non-minimally invasive Hurthle cell carcinoma is typically treated by a total thyroidectomy followed by radioactive iodine therapy.
- A Hurthle cell adenoma or a minimally invasive tumor can be treated by a thyroid lobectomy, although some surgeons will perform a total thyroidectomy to prevent the tumor from reappearing and metastasizing.