Metachronous renal cell carcinoma with delayed testicular metastasis coexisting with synchronous prostatic adenocarcinoma.

Renal cell carcinoma (RCC) is a notorious tumor, known for its unpredictable metastatic behavior; however, metastasis to the testis remains exceptionally rare. We report an unusual case of incidentally detected testicular metastasis from renal cell carcinoma in a patient who was undergoing treatment for coexistent prostatic adenocarcinoma. A 70-year-old man presented with lower urinary tract symptoms and hematuria and was diagnosed with high-grade prostatic adenocarcinoma, for which transurethral resection of the prostate and bilateral orchidectomy were performed. Histopathological examination of the orchidectomy specimen unexpectedly revealed metastatic RCC. On reviewing prior medical records, a history of left radical nephrectomy for clear cell RCC 7 years earlier was noted, confirming a late and isolated ipsilateral testicular metastasis. Subsequent imaging did not demonstrate disease at any other site. This case highlights the remarkable latency and unpredictable metastatic potential of RCC and emphasizes the importance of careful histopathological evaluation of specimens removed for unrelated primary malignancies.