Bilateral clear cell sarcoma of the kidney

Clear cell sarcoma of the kidney (CCSK) accounts for 2–5% of all pediatric renal malignancies, and is known for its propensity to metastasize to bone and other sites. We are reporting two cases with bilateral CCSK that were diagnosed at our institution. One patient initially presented with bilateral renal masses, as well as pulmonary, hepatic and bone metastasis; while other present only with bilateral masses with no evident distant metastasis. Both patients received aggressive neo-adjuvant chemotherapy to decrease tumor size. One patient completed his designated treatment and initially showed complete remission (CR); eventually suffering from relapse. The other patient’s tumor progressed during the course of chemotherapy. Both cases manifested brain dissemination at the time of relapse or progression. This emphasizes the importance of staging stratification in CCSK. This also illustrates CCSK’s ability to metastasize to bone and other sites including the brain (a primary relapse site in our cases).