Background: Renal metastasis is relatively unusual in patients with differentiated thyroid carcinoma.
Methods: The clinicoradiological parameters of a series of patients with differentiated thyroid carcinoma and renal metastasis were assessed, together with follow-up data.
Results and conclusion: The series comprised 4 male patients over the age of 45 years with extensive disease at the primary site. Retro-sternal extension of a large goitre was observed in three patients. The primary tumour was 4 cm or larger in all patients (range, 4–14 cm), and three patients had associated lymph node metastasis. None had any genitourinary symptoms at presentation. Two patients had isolated renal metastases with no other distant metastases, while the others had extensive multi organ involvement. The bilateral occurrence of lesions was a hallmark, being observed in all cases. Ultrasound-guided fine needle aspiration cytology and ¹³¹I scintigraphy were pivotal in confirming the diagnosis. Evidence of ‘flip-flop’ between ¹³¹I study and fluoro-deoxyglucose positron emission tomography was noted in one patient, while the other three demonstrated concordant lesions in both modalities. At a minimum followup period of four years after diagnosis, three patients demonstrated stable disease with radioiodine therapy, and one had expired due to a poorly differentiated lung carcinoma which developed subsequently.