Metastatic Thyroid Carcinoma to the Kidneys Presenting Initially as Bilateral Renal Masses: A Rare Case Report and Literature Review

Thyroid cancers exist in multiple forms. Papillary and follicular carcinomas of the thyroid are often referred to as well-differentiated thyroid cancers. Well-differentiated thyroid cancers rarely present as a distant metastatic cancer on initial diagnosis. Papillary thyroid cancer tends to have a good prognosis; however, if distant metastasis of PTC is present, there is usually a poor clinical outcome with a less favorable prognosis. In this study, we report a 90-year-old female who presented with right-sided abdominal discomfort. A renal ultrasound revealed bilateral upper pole renal masses. A percutaneous biopsy was ordered, and the microscopic examination revealed bilateral renal metastasis with a follicular variant of papillary thyroid carcinoma. The patient underwent thyroidectomy and sustained radiation therapy for her bilateral renal metastases. She died 6 years after her initial diagnosis, due to sepsis. This is the second study in literature to report bilateral renal metastasis of follicular variant of papillary thyroid cancer.