Abstract
Background: Yolk sac tumor is a germ cell neoplasm that arises predominantly in the gonads, but can also derive from somatic neoplasms in extragonadal locations. These cases have been denominated recently as “somatically derived Yolk sac tumors”, and have been documented in several locations, although reports from the urinary tract are scarce. To our knowledge, this is the first report of a Yolk sac tumor derived from urothelial carcinoma. Case presentation: We present a unique case of a 76-year-old man with a recurrent urinary bladder tumor, initially interpreted as a high grade urothelial carcinoma with glandular differentiation. In the recurrent tumor, diverse histological patterns were identified, including glandular, hepatoid and sarcomatoid. This tumor showed positivity for AFP, GLP3 and SALL4, and negativity for CK7 and EMA. Fluorescent in situ hybridization study showed a polysomic pattern of chromosome 12. All these findings led to the final diagnosis of a Yolk sac tumor derived from urothelial carcinoma. Conclusions: Somatically derived Yolk Sac tumors should be considered in the differential diagnosis of a high grade urothelial carcinoma, particularly when glandular and other unusual patterns are observed. Key words: Yolk sac tumor, somatically derived, urothelial carcinoma, urinary bladder, case report.
Yolk sac tumor differentiation in urothelial carcinoma of the urinary bladder: a case report and differential diagnosis