Resident Physician University of California Riverside Redlands, CA, United States
Background: Undifferentiated small blue round cell sarcomas have several differential diagnoses, including Wilms’ tumor, Ewing's sarcoma/primitive neuroectodermal tumor (ES/PNET), and Desmoplastic Small Round-cell Tumor (DSRCT). They primarily affect children or young adolescent populations and are relatively rare to be diagnosed among the adult population. As a result, the treatment is controversial and lacks evidence supporting it.
Methods: This 72-year-old man with an undifferentiated malignant small blue round cell tumor in his right kidney was found to have mixed immunocytochemical (IHC) staining in both Wilms’ tumor and ES/PNET. However, since WT-1 was detected from IHC staining and fluorescence in situ hybridization (FISH) showed no evidence of a translocation pattern of EWSR1 (22; q12) or an EWS-WT1 transcript (t(11;22)(p13;q12)), the findings favored a diagnosis of premature adult Wilms’ tumor.
Results: Adult Wilms’ tumors also showed varying characteristics compared to pediatric Wilms’ tumors, including incidence, the stage when diagnosed, and prognosis. Adult patients diagnosed with Wilms' tumor are suggested to follow pediatric protocol. Patients with stage I with favorable histology (FH) adult Wilms’ tumor should combine two chemotherapy drugs (AMD+VCR) without radiation therapy. However, for patients with adult Wilms’ tumors with staging II or higher, a three-drug chemotherapy regimen with actinomycin+vincristine+doxorubicin, accompanied by radiation therapy, is recommended. Since the high cure rate of Wilms’ tumors from chemotherapy, there is no current evidence of the effectiveness of immune checkpoint inhibitors (ICIs) in Wilms’ tumors.
Conclusions: There is no standardized treatment for either adult Wilms’ tumors or adult ES/PNET in the kidney, but management generally includes chemotherapy with/without radiation therapy, depending on the staging. In adult Wilms’ tumors, the current recommendation is to follow pediatric guidelines involving chemotherapy, surgical resection, and radiotherapy and adjust accordingly. Future studies are essential for establishing standardized management of adult Wilms’ tumors.
