Wilms tumor in adults—an unusual encounter: a case report

BACKGROUND: Wilms tumor, or nephroblastoma, arises from embryonal metanephric blastemal cells and is the most common renal malignancy in the pediatric population. However, its occurrence in adults is extremely rare, with only a limited number of cases documented in the literature. In adults, renal masses most commonly turn out to be renal cell carcinomas, which can closely mimic Wilms tumor on imaging, posing a significant diagnostic challenge. Particularly in resource-limited settings, definitive diagnosis is often established only after histopathological evaluation of nephrectomy specimens. CASE PRESENTATION: We present the case of a 24-year-old Indian woman who presented with a progressively enlarging lump in the right flank. The subsequent investigations revealed a right renal mass, suspected to be malignant, for which the patient underwent a right radical nephrectomy. Histopathological examination confirmed the diagnosis of adult Wilms tumor (nephroblastoma). CONCLUSION: This case highlights the rare occurrence of Wilms tumor in an adult female and underscores the diagnostic challenges it poses. We aim to contribute to the limited body of literature on adult nephroblastoma and promote awareness of this rare entity among clinicians and pathologists.