Metastases to the kidney from primary lung cancer : clinicopathological analysis of six cases in a single center

OBJECTIVES: Cancer metastasis to the kidney is a rare event. We retrospectively analyzed clinicopathologic characteristics in 6 cases of diagnosed renal metastases from primary lung cancer. We also provide clinical follow-up data and brief review of the literature. METHODS: Immunohistochemistry was used to evaluate the expression of TTF-1, NapsinA, CK7, CK(AE1/AE3), P63, P40, CgA, PAX-8, GATA3 and Ki-67 in primary tumor and metastases. Additionally, the clinical characteristics, imaging features, diagnosis, and treatment were analyzed. RESULTS: With the help of immunohistochemistry and combined clinical history, we found four cases were lung adenocarcinomas, one case was lung squamous cell carcinoma, and the other case was lung small cell carcinoma metastases to the kidney.The patients were all male by gender and had a mean age of 62 years, and metastasis to the left kidney were more universal. Most of the tumors histological grade originating from the lung were poorly-moderately differentiated, and the time to metastasis to the kidney was relatively short for squamous lung cancer and small cell lung cancer, while the time to metastasis for lung adenocarcinoma was related to its degree of differentiation. Overall, we found the prognosis of lung cancer patients with renal metastases were poor especially with multi-site metastases. CONCLUSIONS: Distinguishing primary and secondary tumors of the kidney is essential to guide treatment and prevent unnecessary surgery, so clinical information, radiology, histological correlation of the primary tumor, and immunohistochemical findings help the pathologist determine correct diagnosis.