Unusual Presentation of Nephroblastoma in an Adolescent: A Case of Initial Misdiagnosis as a Renal Abscess.

We present the case of a 15-year-old girl who initially had fever, flank pain, and imaging findings consistent with a renal abscess. She was treated with antibiotics and improved clinically, but follow-up imaging showed incomplete resolution. After one year, she developed a recurrence, and a large renal mass was identified. Radical nephrectomy was performed, and histopathology confirmed a nephroblastoma tumor. This unusual presentation demonstrates that recurrent or incompletely resolving renal collections may hide an underlying malignancy. Clinicians should maintain suspicion for neoplastic causes in such scenarios, even in age groups where infection is more likely.