Comprehensive Treatment of a Rare Primary Mediastinal Yolk SAC Tumour with Immature Teratoma

Primary anterior mediastinal yolk SAC tumours are rare but fatal, and primary mediastinal endodermal sinus tumours with immature teratomas are even rarer.This article reports a 31-year man with a yolk SAC tumour with an immature teratoma who was admitted to the hospital for repeated chest pain for more than 3 months.The patient was admitted with a serum alpha-fetoprotein (AFP) level of 3000 ng/mL (reference value: 0-9 ng/mL).Computed tomography (CT) of the chest revealed a solid mass in the left anterior mediastinal area, left lung inflammation, and a small amount of effusion in the left pleural cavity.CT-guided biopsy for diagnosis indicated endodermal sinus tumour.On September 12, 2018, the tumour was resected by a median anterior thoracotomy under general anaesthesia.Left upper lobectomy, partial pericardial resection, pericardial repair, and bilateral closed chest drainage were performed.Postoperative pathological results revealed germ cell-derived malignant tumour, consisting of 70% endodermal sinus tumour, and 30% immature teratoma.Next-generation sequencing of tissue specimens after surgery revealed DDR2, exon 5, c.286T> G, p.F96V, and a mutation abundance of 49.58%; PDL1 testing of tissue specimens showed a low expression level (<1%).The patient was treated with carboplatin plus docetaxel for four cycles.A re-examination on February 26, 2019, of the chest CT revealed a new anterior mediastinal mass, suggesting recurrence of the tumour after surgery and metastasis to the left posterior pleura.The patient died of recurrence and metastasis in August 2019.