Objective: To study the clinicopathological, immunohistochemical features and the histogenesis of clear cell sarcoma of the kidney (CCSK).
Methods: CCSK specimens from 45 pediatric cases, including 31 male and 14 female with an age range from 3 months to 12 years (mean of 3.2 years), were retrieved. Routine pathological, immunohistochemical and electron microscopic methods were utilized to analyze the CCSK specimens.
Results: 35 of the 45 cases were followed from 6 to 192 months. 15 patients presented with bone metastases, 6 had lung or liver metastases, 8 recurred and 20 died. Age and clinical stage at diagnosis correlated with the rate of survival. Histologically, the classic pattern of CCSK consisted of cells with pale cytoplasm, fine nuclear chromatin and indistinct nucleoli separated by an arborizing fibrovascular stroma. Other patterns were identified, including myxoid, spindle, palisading, epithelioid, sclerosing, cellular, cystic, and angiectatic. All tumors contained multiple patterns. Immunohistochemically, all cases were positive for vimentin, but negative for EMA, CK, desmin, actin, S-100, NSE, CD99, CD34 and LCA. Electron microscopy of 9 cases showed features of primitive cell conjunction and few organelles.
Conclusion: CCSK is a common renal neoplasm of childhood. CCSK may arise from renal mesenchymal cells and has the propensity to metastasize to the bone with poor clinical outcome.