Complete radiological and biochemical remission at 26 months in a young adult with primary mediastinal yolk sac tumor: a case report and literature review on multimodal management

Background Primary mediastinal yolk sac tumor (PMYST) is an extremely rare and highly malignant germ cell tumor that predominantly affects young males and is associated with a poor prognosis. Case presentation We present the case of a 23-year-old non-smoking male diagnosed with stage III (cT4N0M0) PMYST who received comprehensive treatment guided by a multidisciplinary team (MDT). The treatment regimen included 5 cycles of neoadjuvant chemotherapy with BEP (bleomycin, etoposide, and cisplatin), followed by radical surgery, postoperative radiotherapy, and 4 cycles of adjuvant chemotherapy. Post-treatment, the patient's serum tumor markers normalized, with a partial radiological response (PR) and sustained biochemical remission. As of the latest follow-up in August 2025 (26 months after diagnosis), the patient remains in complete radiological and biochemical remission with no signs of recurrence. Conclusions This case demonstrates that an intensive MDT-guided multimodal approach incorporating aggressive neoadjuvant chemotherapy, radical surgery, and consolidative sequential radiotherapy and chemotherapy may lead to encouraging outcomes, including the achievement of complete radiological and biochemical remission documented at 26 months. However, this case is more reflective of individualized treatment for a specific patient, and it also highlights the need for intensified surveillance beyond two years.