Clear cell sarcoma of the kidney is not a Wilms tumor variant, but it is an important primary renal tumor associated with a higher rate of relapse and death than favorable-histology (FH) Wilms tumor. The classic pattern of clear cell sarcoma of the kidney is defined by nests or cords of cells separated by regularly spaced fibrovascular septa. In addition to pulmonary metastases, clear cell sarcoma also spreads to bone, brain, and soft tissue. (Refer to the Wilms tumor Clinical Features and Diagnostic and Staging Evaluation sections of this summary for more information about the clinical features and diagnostic evaluation of childhood kidney tumors.)
The histiocytic diseases in children and adults include three major classes of disorders. Only Langerhans cell histiocytosis (LCH), a dendritic cell disorder, is discussed in detail in this summary. Erdheim-Chester disease (primarily found in adults) and juvenile xanthogranuloma (diagnosed in children and adults) are macrophage disorders. Other disorders of the macrophage/monocytoid lineages include Rosai-Dorfman disease and hemophagocytic lymphohistiocytosis. Malignant disorders include malignant...
While little is known about the biology of clear cell sarcoma of the kidney, the t(10;17)(q22;p13) translocation has been reported. As a result of the translocation, the YWHAE-FAM22 fusion transcript is formed; this transcript was detected in 12% of cases of clear cell sarcoma of the kidney in one series. 17p13 is the site of the P53 gene; however, this gene does not show abnormal expression and most likely is not involved. Gene expression studies revealed the upregulation of neural markers, with ensuing activation of the sonic hedgehog and Akt pathways. When DNA methylation profiling was used, the epigenetic characteristics of clear cell sarcoma of the kidney, rhabdoid tumor of the kidney, and Ewing sarcoma of the kidney, in comparison with those of the non-neoplastic kidney, exhibited distinct DNA methylation profiles in a tumor type-specific manner. The DNA methylation pattern of the THBS1 CpG site is sufficient for distinction of clear cell sarcoma of the kidney from other pediatric renal tumors.
Younger age and stage IV disease have been identified as adverse prognostic factors for event-free survival (EFS).
Historically, relapses have occurred in long intervals after the completion of chemotherapy (up to 10 years); however, with current therapy, relapses after 3 years are uncommon. The brain is a frequent site of recurrent disease, suggesting that it is a sanctuary site for cells that are protected from the intensive chemotherapy that patients currently receive.[5,7,8] An awareness of the clinical signs of recurrent disease in the brain is important during regular follow-up. There are no standard recommendations for the frequency of brain imaging during follow-up.