Adult Wilms' Tumor during Pregnancy: A Rare and Challenging Clinical Scenario with Literature Review.

Wilms' tumor (nephroblastoma) is a predominantly pediatric malignancy and is exceedingly rare in adults, particularly during pregnancy. We report a case of a 26-year-old South Asian woman diagnosed with a left-sided large retroperitoneal mass incidentally during the second trimester of pregnancy. The patient underwent radical nephrectomy during pregnancy, and histopathology and immunohistochemistry confirmed high-risk nephroblastoma. The patient was closely monitored throughout the pregnancy period and delivered a healthy preterm infant via cesarean section. Systemic chemotherapy was started after the delivery. Despite multimodal management, including surgery and systemic chemotherapy, the disease showed aggressive progression with widespread metastases. The patient required multiple lines of chemotherapy and palliative care, with partial symptomatic improvement. This case highlights the diagnostic and therapeutic challenges of managing adult Wilms' tumors during pregnancy, the importance of multidisciplinary care, and the need for timely intervention to optimize maternal and fetal outcomes.