Solitary renal metastasis of follicular thyroid carcinoma with cervical nodal deposits

Abstract

Differentiated thyroid cancer includes both papillary thyroid carcinoma and follicular thyroid carcinoma (FTC). It is known to be indolent and is usually limited to the thyroid at the time of presentation. Synchronous case presentation of a thyroid swelling with a regional lymph node and solitary distant renal metastasis is a not so common presentation in FTC. We report the clinical, radiological, and pathological features in addition to management of a case of FTC in a 56-year-old female who presented with a neck swelling and upon diagnostic workup, a solitary renal swelling was discovered, which was diagnosed as metastasis from the original thyroid lesion. Our case shows both regional lymphatic spread and distant hematogenous spread to the kidney. Lymphatic spread has been described in the literature with FTC, but is uncommon. Distant metastasis through hematogenous spread can occur but most often to lungs and bones. Hematogenous metastasis to the kidney is extremely rare. Aim: To present a very rare presentation of FTC with the kidney being the only site for hematogenous metastasis and conduct a focused literature review on similar cases and illustrate the pathological and molecular bases for diagnosis.