SAT569 Papillary Thyroid Carcinoma With Renal Metastasis Treated With Radioactive Iodine: A Case Report

Disclosure: A.A. Apa-ap: None. M.B. Sedurante: None. J. Lacuata: None. J. Gacula: None. V. Lee: None. M.L. Hernandez: None. INTRODUCTION. Papillary thyroid cancer (PTC) is one of the most treatable cancers in comparison to undifferentiated thyroid malignancies. It advances slowly, and there is only 1-4 percent of cases of distant metastases. Renal involvement from PTC is very rare with an incidence of 0.47 percent. CASE DESCRIPTION. This paper describes a 34-year-old Filipino female presenting with an 8-year history of hoarseness and a gradually enlarging anterior neck mass. Metastatic workup revealed innumerable bilateral pulmonary nodules bilateral cervical lymphadenopathy, and bilateral renal mass on CT scan. The right pole of the kidney shows a solid heterogeneously enhancing partially-exophytic focus measuring 4.9 x 4.2 x 4.3cm likely a primary renal cell carcinoma versus metastasis. The left renal mass shows a hypodense non-enhancing partially-exophytic focus measuring 3.9 x 3.6 x 3.6cm probably a renal cyst. Clinically, the patient did not show any urinary symptoms and creatine clearance was normal. The patient underwent total thyroidectomy and neck dissection and histopathology revealed PTC. The patient underwent simultaneous ultrasound right renal mass biopsy which revealed few fragments of thyroid tissues with atypia most likely representative of metastasis of PTC. Since the radiographic finding was suggestive of a renal cyst, the left renal mass was not biopsied. Patient refused nephrectomy and underwent 1 cycle of Radioactive Iodine (RAI) Therapy. Post therapy whole body scan showed mildly increased and diffuse tracer uptake activity in bilateral lungs and large avid focus, approximately 5.0 x 4.4 cm, seen in the inferior pole of the right kidney. Surveillance showed increased thyroglobulin. To date, the patient still refused surgery and is contemplating undergoing another cycle of RAI therapy. DISCUSSION. Due to the rarity of the metastatic site, the ideal course of treatment for this illness is unknown. To our knowledge, there are only approximate of 30 case reports on WDTC with renal metastasis in the literature. Presentation: Saturday, June 17, 2023