The mystic thyroid nodule: A cytologist's confront.

Metastatic thyroid carcinoma is clinically silent and found only at autopsy in most instances. Renal cell carcinoma (RCC) is the most common and constitutes 56% of all secondary malignancies. However, preoperative distinction between primary and secondary thyroid neoplasms is often challenging. Fine needle aspiration is helpful in establishing a correct preoperative diagnosis. A local surgical resection is curative if prompt preoperative diagnosis is established. We hereby report a case of isolated metastatic RCC to the thyroid in a 65-year-old woman, diagnosed by fine needle aspiration cytology and later confirmed with histopathological examination.