Yolk sac tumors are testicular germ-cell tumors of the non-seminoma type. In cattle, this neoplasm is very rare and to date has only been described three times. In human males, it usually occurs in infants and children. Immunohistochemistry provides solid criteria for diagnostics. Especially present pathognomonic Schiller-Duval bodies are helpful for identification. In this report, a 32-day-old Holstein Friesian calf presented with a highly enlarged right testis. Sonographic examination was performed and blood samples were taken to measure testosterone and estrogen levels. Furthermore, the testis was surgically removed and macroscopically, histologically, and immunohistochemically examined which lead to the diagnosis of testicular yolk sac tumor. The second testis was descended until the age of nine months and histology revealed impaired spermatogenesis. This report provides the first sonographic images of bovine testicular yolk sac tumor as well as the first information about hormone levels in calves with this neoplasm. It also shows the importance to combine anamnesis, histomorphological, and immunohistochemical findings in order to diagnose yolk sac tumors when pathognomonic structures are not present.

中文翻译：

---

荷斯坦黑白花小牛的睾丸卵黄囊肿瘤和精子发生受损。

卵黄囊肿瘤是非精原细胞瘤类型的睾丸生殖细胞肿瘤。在牛中，这种肿瘤非常罕见，迄今为止仅被描述了三次。在人类男性中，它通常发生在婴儿和儿童中。免疫组织化学为诊断提供了坚实的标准。特别是当前的人机工程学Schiller-Duval体有助于识别。在这份报告中，一头32天大的荷斯坦黑白花小牛的右侧睾丸高度增大。进行超声检查并采集血样以测量睾丸激素和雌激素水平。此外，通过手术切除睾丸并进行肉眼观察，组织学和免疫组织化学检查，从而诊断出睾丸卵黄囊肿瘤。第二个睾丸下降直到九个月大，并且组织学显示精子发生受损。该报告提供了牛睾丸卵黄囊肿瘤的第一张超声图像，以及有关这种肿瘤的犊牛中激素水平的第一信息。它还显示了结合记忆检查，组织形态学和免疫组织化学检查结果的重要性，以便在不存在病理组织学结构时诊断卵黄囊肿瘤。