en Oncology Oncology case report case report <span style="font-size:14px;"><span style="font-family:Times New Roman;"><span style="color:#0000ff;"><strong><em>Background</em></strong><em>:</em> </span>Wilms&#39; tumor, nephroblastoma, is an extremely uncommon kidney tumor of adulthood. We reported a woman with a huge kidney mass diagnosed with nephroblastoma.<br> <span style="color:#0000ff;"><strong><em>Case presentation</em></strong><em>:</em></span> A 39-year-old female was assessed due to right flank pain. CT scan revealed a mass measuring 128&times;100 mms involving the upper portion of the right kidney. The patient underwent nephrectomy, and the diagnosis of adult Wilms&#39; tumor was confirmed based on the morphological and immunohistochemical findings.<br> <span style="color:#0000ff;"><strong><em>Conclusion</em></strong><em>:</em></span> In adult patients with flank pain and renal mass, the diagnosis of Wilms&#39; tumor should be pronounced in the absence of histopathologic features of renal cell carcinoma.</span></span> case report, Wilms tumor, nephroblastoma, adult 421 425 http://caspjim.com/browse.php?a_code=A-10-1851-1&slc_lang=en&sid=1 Mahdi Farzadnia farzadniam@mums.ac.ir 100319475328460031201 100319475328460031201 No Department of Pathology, Mashhad University of Medical Sciences, Mashhad, Iran Mahboobe Karrabi karrabim941@mums.ac.ir 100319475328460031202 100319475328460031202 Yes Department of Pathology, Mashhad University of Medical Sciences, Mashhad, Iran Hamidreza Ghorbani ghorbanihr@mums.ac.i 100319475328460031203 100319475328460031203 No Kidney transplantation complication research center, Mashhad University of Medical Sciences, Mashhad, Iran