Özet:

Metachronous metastasis of renal cell carcinoma (RCC) to its ureter has been scarcely reported. All such reports have involved clear cell RCC. We report the first ever case of an oncocytic variant of papillary RCC (OPRCC) - an extremely rare variant that spreads to the ipsilateral ureter. A sixty-five-year-old man, diagnosed to have non-metastatic left RCC with renal vein thrombus, underwent radical nephrectomy. Histopathology revealed large cells in papillary and tubular arrangements with abundant granular cytoplasm. On immunohistochemistry, cells strongly expressed Alpha-methylacyl-CoA racemase and were negative for CD10, C-kit, TFE3, and Melan A, hence a diagnosis of OPRCC, type 2 was given. During follow-up six months, he had a fluorodeoxyglucose avid lesion of size 2.8 cm in the proximal aspect of the left ureteric stump. Therefore, we performed robotic excision of the left ureteric stump and bladder cuff with pelvic node dissection. Pathological examination showed a ureteric mass infiltrating the muscularis propria and periureteric adipose tissue with features of OPRCC, similar to the nephrectomy specimen. It was Pax 8 positive with negativity for the urothelial markers Gata 3, uroplakin and p63, consistent with drop metastasis in a known case. Thus, clinicians must bear in mind that ureteric masses are not always of transitional cell variety and non-clear cell RCC can also metastasize to the ureter. This should be considered by pathologists while evaluating kidney specimens showing oncocytic features. This is the first case report of non-clear cell variety of drop metastasis of a rare histological variant of RCC to the ipsilateral ureter.

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