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Clear Cell Sarcoma of Kidney (CCSK) : Differential Diagnosis (continued):
Cellular Congenital Mesoblastic Nephroma (CCMN): CCMN and spindle cell variant of CCSK closely resemble each other. However, CCSK shows diverse morphologic patterns and lacks the t(12;15) translocation resulting in ETV6-NRTK3 fusion - a diagnostic feature of CCMN. CCMN also occurs in a younger patient population (usually by 6 months of age) than CCSK (2-3 years of age).
Fibrohistiocytic Neoplasms: Spindle cell variant of CCSK with tumor cells arranged in haphazard, short intersecting fascicles can mimic fibrohistocytic neoplasms. Pure spindle cell CCSK can resemble monophasic synovial sarcoma. Some cases have the appearance of monomorphic high-grade sarcoma.
Metanephric stromal tumors (MST): MSTs can have storiform, palisaded, and hemangiopericytomatous patterns that can mimic CCSK. However, the nuclei of MST are hyperchromatic unlike those of CCSK.
Cellular Congenital Mesoblastic Nephroma (CCMN): CCMN and spindle cell variant of CCSK closely resemble each other. However, CCSK shows diverse morphologic patterns and lacks the t(12;15) translocation resulting in ETV6-NRTK3 fusion - a diagnostic feature of CCMN. CCMN also occurs in a younger patient population (usually by 6 months of age) than CCSK (2-3 years of age).
Fibrohistiocytic Neoplasms: Spindle cell variant of CCSK with tumor cells arranged in haphazard, short intersecting fascicles can mimic fibrohistocytic neoplasms. Pure spindle cell CCSK can resemble monophasic synovial sarcoma. Some cases have the appearance of monomorphic high-grade sarcoma.
Metanephric stromal tumors (MST): MSTs can have storiform, palisaded, and hemangiopericytomatous patterns that can mimic CCSK. However, the nuclei of MST are hyperchromatic unlike those of CCSK.