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Hürthle cell carcinoma (HCC) is a rare, malignant neoplasm of the thyroid derived from follicular epithelium, composed predominantly of Hürthle (oncocytic) cells. It is considered a variant of follicular thyroid carcinoma (FTC) but exhibits more aggressive behavior, higher recurrence rates, and a lower response to radioactive iodine (RAI) therapy.

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Epidemiology

• Accounts for 3–5% of all thyroid cancers
• More common in women, typically in the 5th–7th decade
• Can occur de novo or evolve from a pre-existing Hürthle cell adenoma
• Higher incidence in iodine-deficient areas

Etiopathogenesis

Cell of Origin

• Follicular epithelial origin
• Hürthle cells are large polygonal cells with:
  • Abundant granular eosinophilic cytoplasm (due to mitochondrial hyperplasia)
  • Round, centrally located nuclei

Genetic Alterations

• Frequent chromosomal losses (esp. chromosomes 1p, 3, 9q, 16q)
• Less commonly harbor BRAF or RET/PTC mutations
• May show p53 mutations and complex karyotypes in advanced cases

Pathology

Gross Features

• Solitary, solid, encapsulated mass