Differential diagnosis of renal tumors with tubulopapillary architecture in children and young adults: a case report and review of literature.

BACKGROUND Tumors of the kidney are uncommon in children and young adults. Accurate classification is crucial for both prognostication and therapeutic intervention. However, majority of the tumors in this age group have unusual morphology that renders classification challenging. Tubulopapillary architecture is one of the most common morphological patterns observed in renal tumors of children and young adults. METHODS A patient with epithelial predominant Wilms tumor was reported. Differential diagnosis of renal tumors with tubulopapillary morphology was discussed with an emphasis on the histological and immunohistochemical features, and the literature was reviewed. RESULTS A 25 year-old female patient presented with bilateral multilocular cystic masses. She underwent right radical nephrectomy and left partial nephrectomy. The pathological examination revealed a tumor with tubulopapillary architecture which was lined with low columnar epithelial cells. During the work-up of this case, several entities were considered and ruled out by careful gross, microscopic examination and prudent use of immunohistochemistry. The tumor cells were positive for WT-1, and variably positive for cytokeratin AE1/3, CD56, CD57, and negative for cytokeratin 7 and EMA. Fluorescent in-situ hybridization revealed no gain of chromosome 7 and 17. A diagnosis of epithelial predominant adult Wilms tumors was rendered for both kidneys. The patient received systemic chemotherapy and radiation to the remnant left kidney and was free of disease three years after the initial surgery. CONCLUSION The differential diagnosis of renal tumors with tubulopapillary features in children and young adults include papillary renal cell carcinoma, metanephric adenoma, epithelial predominant Wilms tumor, translocation renal cell carcinoma and metastatic adenocarcinoma to the kidney. An accurate classification relies on careful examination of clinical and pathological features and immunohistochemical characteristics.