Papillary thyroid carcinoma presenting as a primary renal tumor with multiple pulmonary and bone metastases: a case report.

Background: Papillary thyroid carcinoma is the most common endocrine malignancy. Distant metastasis from differentiated thyroid carcinoma is infrequent and the metastasis rate of papillary thyroid carcinoma is lower than that of follicular thyroid carcinoma. Distant metastases from differentiated thyroid carcinoma are usually seen in the lungs and bones; however, renal metastasis is very rare.

Case Presentation: Here we describe an 85-year-old Caucasian woman who presented with right flank pain 10 years ago. We describe a case of papillary thyroid carcinoma presenting as a primary renal tumor with extensive pulmonary and bone metastases. Abdominal screening with computed tomography revealed a mass on her right kidney, which was considered a primary renal cell carcinoma and she underwent a right nephrectomy. Unexpectedly, papillary thyroid carcinoma metastasis was diagnosed from demonstrative histopathological findings, such as positive immunoperoxidase staining for thyroglobulin. A total thyroidectomy was performed. Unenhanced thoracic computed tomography and skeletal scintigraphy revealed bilateral multiple nodules in her lungs and bone metastasis on T10 vertebra and right sacroiliac joint. Initially, 30 Gy radiotherapy was implemented to her T9-10 vertebrae and then she was treated with a total of 800 mCi radioactive iodine for ablation. A radioactive iodine whole body scan was performed after each 200 mCi and continuous progression was shown in each scan. After she was lost to follow-up for 3 years, she referred to our clinic again with a draining mass on her neck and we planned radiotherapy to this giant mass.

Conclusion: Our patient was surprisingly still alive after metastatic disease was diagnosed 10 years ago and she had no major complaint other than a draining mass on her neck. Our primary aim by sharing this case is to underline potential renal metastasis from papillary thyroid carcinoma. In other words, when approaching primary renal tumors, possible distant metastases of other organs need to be kept in mind for differential diagnosis. In addition, it should be noted that if managed appropriately, the long-term survival in patients with papillary thyroid carcinoma with multiple organ metastases could be encouraging.