Cytologic Features of Renal Carcinoma Associated with Xp11.2 Translocations/ TFE3 Gene Fusions: A Case Report with Voided and Catheterized Urine Cytology and a Literature Review.

BACKGROUND: Renal carcinomas associated with Xp11.2 translocations/TFE3 gene fusions are rare subtypes of renal neoplasm that predominantly occur in younger individuals. There are very few reports describing the cytologic features of these tumors.

CASE: A 27-year-old man presented with hematuria and was found to have a mass in the lower part of the right kidney. Cytology of catheterized urine obtained from the right renal pelvis showed clusters of cells with abundant clear or eosinophilic granular cytoplasm, large round nuclei and prominent nucleoli. Papillary clusters containing thin fibrous stroma were occasionally seen. Voided urine cytology showed similar cell clusters but degeneration made the features obscure. Nephroureterectomy revealed a renal tumor showing a mixed papillary and nested architecture. The diagnosis was confirmed by immunohistochemistry and fluorescence in situ hybridization.

CONCLUSION: The present case indicates that the characteristic features of these tumor subtypes can be retained in urine cytology. Cytology may be enough to suspect these tumors as part of the differential diagnosis when the patient's age and imaging findings are taken into account and may facilitate further studies for a definitive diagnosis.