Hurthle

Hurthle refers to Hurthle cells, a type of epithelial cell also known as oncocytic cells. These cells are characterized by a large size and abundant granular, eosinophilic cytoplasm, reflecting a high mitochondrial content. The nuclei are typically round to oval with a small, sometimes inconspicuous nucleolus. Hurthle cells can appear in various tissues, but they are most prominently described in the thyroid.

In thyroid pathology, Hurthle cells can occur as a reactive or degenerative change (often called Hurthle cell change) in conditions such as Hashimoto’s thyroiditis, multinodular goiter, and Graves’ disease. They also form the defining cell type of oncocytic (Hurthle cell) neoplasms, including Hurthle cell adenoma (benign) and Hurthle cell carcinoma (malignant). Distinguishing carcinoma from adenoma depends on the presence of capsular and/or vascular invasion. Hurthle cell carcinoma can behave more aggressively than other differentiated thyroid carcinomas and may metastasize.

Beyond the thyroid, Hurthle (oncocytic) cells can be observed in other tissues, including salivary glands, where oncocytic changes may occur in various neoplasms or inflammatory processes. In pathology, the terms Hurthle cell and oncocyte are often used interchangeably, though usage can vary by organ and context.

Diagnosis is based on histopathology, with immunohistochemical and molecular studies supporting classification and helping to differentiate benign versus malignant lesions. The eponym reflects the historical description of these distinctive cells.