LAUSR

Background Crizotinib is the first tyrosine kinase inhibitor approved for the treatment of anaplastic lymphoma kinase (ALK) rearranged non-small cell lung cancer (NSCLC). An increased incidence of renal cysts has been described during the crizotinib treatment. Case Presentation We herein report the case of a 74-year-old woman who received crizotinib for metastatic ALK-positive NSCLC. During the crizotinib treatment, complex renal cystic lesions with invasion of perirenal spaces and iliopsoas muscle appeared; two complex hepatic cysts were also observed. Almost all lesions disappeared after switching to alectinib, a second-generation ALK inhibitor. Conclusion It would seem that alectinib is able to reduce in size and number hepatic and renal cysts caused by the crizotinib treatment. Nevertheless, further studies are needed to clarify the role of both crizotinib in the onset of renal and hepatic cysts and alectinib in their disappearance.