Crizotinib-associated Renal Cyst Formation in a Pediatric Patient With ALK+ Epithelioid Inflammatory Myofibroblastic Sarcoma.

BACKGROUND: Crizotinib is a first-generation tyrosine kinase inhibitor used for anaplastic lymphoma kinase (ALK) positive cancers. Simple and complex renal cyst formation is a rare complication of crizotinib use that has been reported previously in the adult population. CASE: We report a case of a right renal mass in a 17-year-old with ALK-positive epithelioid inflammatory myofibroblastic sarcoma treated with Crizotinib. After cessation of Crizotinib and initiating Alectenib, a second generation ALK inhibitor, the mass decreased in size and the patient remained asymptomatic without evidence of recurrence at three months of follow-up.