Rare Giant Pure Yolk Sac Tumor Originating from Cryptorchidism in an Adult.

Cryptorchidism is a well-established risk factor for testicular cancer. Among adult male patients, pure testicular yolk sac tumors (YSTs) are rare, and those arising from cryptorchidism in adult males are even less common. We report a case of a 35-year-old male with a giant YST originating from cryptorchidism, with no distant metastasis detected preoperatively. The initial treatment plan was radical orchiectomy combined with postoperative chemotherapy for curative intent, but direct surgery was extremely challenging due to the large tumor size. Therefore, we attempted neoadjuvant chemotherapy to facilitate surgical resection. To our knowledge, there are relatively few reports on the use of neoadjuvant chemotherapy to reduce tumor burden prior to testicular tumor resection. The patient received four cycles of neoadjuvant chemotherapy before surgery, after which the tumor volume decreased, and the levels of alpha-fetoprotein (AFP) and lactate dehydrogenase (LDH) also dropped. Unfortunately, Liver metastases were detected during the reexamination on the 28th post-operative day, and lung metastases were identified in another reexamination on the 85th post-operative day. Regrettably, the patient refused further treatment and discontinued it, and we eventually lost follow-up. Post-pubertal YSTs are highly aggressive, and early detection and intervention are crucial for patients suspected of having cryptorchidism. Neoadjuvant chemotherapy can be considered as an adjuvant therapeutic strategy for reducing tumor burden in testicular tumors.