Clinicoradiological characteristics of patients with differentiated thyroid carcinoma and renal metastasis: case series with follow up

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 4cm or larger in all patients (range, 4-14cm), and three patients had associated lymph node metastasis. None had any genito-urinary 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 I-131 scintigraphy were pivotal in confirming the diagnosis. Evidence of flip-flop' between I-131 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 follow-up 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.