RESUMEN
BACKGROUND: Metastases from renal cell carcinoma to the thyroid gland are uncommon and the clinical course often prolonged. We wished to determine the incidence of such metastases in surgical biopsy records from two Norwegian hospitals. MATERIAL AND METHOD: The archives of the Department of Pathology at Nordland Hospital Bodø (for the period 2002-11) and the Department of Pathology and Medical Genetics at St. Olav's Hospital (for the period 1986-2011) were searched for possible metastases from renal cell carcinoma to the thyroid gland. Biopsy and clinical records were later reviewed to determine sex, age, symptoms, the results of preoperative examinations, tumour size, immune profile and treatment, as well as subsequent clinical course and survival. RESULTS: The biopsy records of five patients, four females and one male, between the ages of 58 and 89 years showed metastases in the thyroid gland that were morphologically and immunohistochemically identical to the renal cell carcinomas that had previously been removed from these patients. A considerable length of time had elapsed, up to 25 years (median 21 years), before the metastases appeared and gave rise to clinical symptoms. All of the patients underwent surgery. Survival following hemithyroidectomy ranged from two months to 13 years. One patient was still alive when the material was reviewed. INTERPRETATION: Metastases from renal clear cell carcinoma to the thyroid gland can occur many years after removal of the primary tumour and produce clinical symptoms such as multinodular goitres. Surgery is indicated if there are no other metastases. The prognosis is good in some patients.