Clear cell sarcoma of the pediatric kidney: Detailed description and analysis of variant histologic patterns of a tumor with many faces

Clear cell sarcoma of the kidney is the most frequently misdiagnosed renal tumor in children. The majority of tumors present the classic histologic pa ttern, which allows a definitive diagnosis. However, there are unusual case s with lack of "clear'' appearance of tumor cells, predominance or exclusiv e presence of variant histologic patterns, and presence of "neoplastic" app earing entrapped tubules. Furthermore, a small biopsy specimen may not show the classic histologic pattern. These tumors present a diagnostic challeng e for the practicing pathologist who should be aware of the deviations from the classic histologic features in order to make a correct diagnosis.