Metastatic Yolk Sac Tumor in the Urinary System: a Case Report and Literature Review

A testicular cancer is one of the most common malignancies observed in males between the ages of 15 and 35. Testicular-origin yolk sac tumors typically manifest as large, painless, voluminous masses. In nearly all cases with pure or mixed forms of yolk sac tumors, significantly elevated serum alpha-fetoprotein (AFP) levels are detected. Microscopically, the appearance of a yolk sac tumor is the same regardless of patient age and primary site. Observation of Schiller-Duvall bodies is pathognomic for yolk sac tumors. Immunohistochemically, yolk sac tumors are positive for AFP, CK AE1/AE3, Glypican-3 and SALL4, and negative for EMA and CK7. Pure yolk sac tumors are very rare in adults, and only a few cases have been reported in the literature. While adult and prepubertal yolk sac tumors may be histologically similar, it is noted that they tend to metastasize more frequently in adults and exhibit a poorer prognosis. This phenomenon is attributed to the tumor being poorly differentiated in adults. The preferred primary treatment for advanced disease is three to four cycles of BEP (bleomycin, etoposide, cisplatin) chemotherapy followed by resection of residual tumor In our case, we observe a yolk sac tumor that has metastasized synchronously to the renal pelvis, ureter, and bladder. In these patients, elevated serum AFP levels are noted. Given that enzyme levels are not routinely assessed in preoperative and postoperative monitoring of adult patients with urothelial carcinoma, it is important to recognize that uncommon histological patterns in urothelial neoplasms may be unnoticed.